diff --git a/app/code/Magento/QuoteGraphQl/Model/Resolver/ApplyCouponToCart.php b/app/code/Magento/QuoteGraphQl/Model/Resolver/ApplyCouponToCart.php
index 0af35354758c..5429d5333b25 100644
--- a/app/code/Magento/QuoteGraphQl/Model/Resolver/ApplyCouponToCart.php
+++ b/app/code/Magento/QuoteGraphQl/Model/Resolver/ApplyCouponToCart.php
@@ -50,12 +50,12 @@ public function __construct(
      */
     public function resolve(Field $field, $context, ResolveInfo $info, array $value = null, array $args = null)
     {
-        if (!isset($args['input']['cart_id'])) {
+        if (!isset($args['input']['cart_id']) || empty($args['input']['cart_id'])) {
             throw new GraphQlInputException(__('Required parameter "cart_id" is missing'));
         }
         $maskedCartId = $args['input']['cart_id'];
 
-        if (!isset($args['input']['coupon_code'])) {
+        if (!isset($args['input']['coupon_code']) || empty($args['input']['coupon_code'])) {
             throw new GraphQlInputException(__('Required parameter "coupon_code" is missing'));
         }
         $couponCode = $args['input']['coupon_code'];
diff --git a/app/code/Magento/QuoteGraphQl/Model/Resolver/Cart.php b/app/code/Magento/QuoteGraphQl/Model/Resolver/Cart.php
index 2df31841366a..db74b1fa4174 100644
--- a/app/code/Magento/QuoteGraphQl/Model/Resolver/Cart.php
+++ b/app/code/Magento/QuoteGraphQl/Model/Resolver/Cart.php
@@ -37,7 +37,7 @@ public function __construct(
      */
     public function resolve(Field $field, $context, ResolveInfo $info, array $value = null, array $args = null)
     {
-        if (!isset($args['cart_id'])) {
+        if (!isset($args['cart_id']) || empty($args['cart_id'])) {
             throw new GraphQlInputException(__('Required parameter "cart_id" is missing'));
         }
         $maskedCartId = $args['cart_id'];
diff --git a/app/code/Magento/QuoteGraphQl/Model/Resolver/RemoveCouponFromCart.php b/app/code/Magento/QuoteGraphQl/Model/Resolver/RemoveCouponFromCart.php
index 68925c6e8944..5a708ceaedc2 100644
--- a/app/code/Magento/QuoteGraphQl/Model/Resolver/RemoveCouponFromCart.php
+++ b/app/code/Magento/QuoteGraphQl/Model/Resolver/RemoveCouponFromCart.php
@@ -50,7 +50,7 @@ public function __construct(
      */
     public function resolve(Field $field, $context, ResolveInfo $info, array $value = null, array $args = null)
     {
-        if (!isset($args['input']['cart_id'])) {
+        if (!isset($args['input']['cart_id']) || empty($args['input']['cart_id'])) {
             throw new GraphQlInputException(__('Required parameter "cart_id" is missing'));
         }
         $maskedCartId = $args['input']['cart_id'];
diff --git a/app/code/Magento/QuoteGraphQl/Model/Resolver/RemoveItemFromCart.php b/app/code/Magento/QuoteGraphQl/Model/Resolver/RemoveItemFromCart.php
index c8f0ef06c759..63e66f121f55 100644
--- a/app/code/Magento/QuoteGraphQl/Model/Resolver/RemoveItemFromCart.php
+++ b/app/code/Magento/QuoteGraphQl/Model/Resolver/RemoveItemFromCart.php
@@ -14,7 +14,7 @@
 use Magento\Framework\GraphQl\Exception\GraphQlNoSuchEntityException;
 use Magento\Framework\GraphQl\Query\ResolverInterface;
 use Magento\Framework\GraphQl\Schema\Type\ResolveInfo;
-use Magento\Quote\Api\GuestCartItemRepositoryInterface;
+use Magento\Quote\Api\CartItemRepositoryInterface;
 use Magento\QuoteGraphQl\Model\Cart\GetCartForUser;
 
 /**
@@ -23,25 +23,25 @@
 class RemoveItemFromCart implements ResolverInterface
 {
     /**
-     * @var GuestCartItemRepositoryInterface
+     * @var GetCartForUser
      */
-    private $guestCartItemRepository;
+    private $getCartForUser;
 
     /**
-     * @var GetCartForUser
+     * @var CartItemRepositoryInterface
      */
-    private $getCartForUser;
+    private $cartItemRepository;
 
     /**
-     * @param GuestCartItemRepositoryInterface $guestCartItemRepository
      * @param GetCartForUser $getCartForUser
+     * @param CartItemRepositoryInterface $cartItemRepository
      */
     public function __construct(
-        GuestCartItemRepositoryInterface $guestCartItemRepository,
-        GetCartForUser $getCartForUser
+        GetCartForUser $getCartForUser,
+        CartItemRepositoryInterface $cartItemRepository
     ) {
-        $this->guestCartItemRepository = $guestCartItemRepository;
         $this->getCartForUser = $getCartForUser;
+        $this->cartItemRepository = $cartItemRepository;
     }
 
     /**
@@ -49,20 +49,20 @@ public function __construct(
      */
     public function resolve(Field $field, $context, ResolveInfo $info, array $value = null, array $args = null)
     {
-        if (!isset($args['input']['cart_id'])) {
-            throw new GraphQlInputException(__('Required parameter "cart_id" is missing'));
+        if (!isset($args['input']['cart_id']) || empty($args['input']['cart_id'])) {
+            throw new GraphQlInputException(__('Required parameter "cart_id" is missing.'));
         }
         $maskedCartId = $args['input']['cart_id'];
 
-        if (!isset($args['input']['cart_item_id'])) {
-            throw new GraphQlInputException(__('Required parameter "cart_item_id" is missing'));
+        if (!isset($args['input']['cart_item_id']) || empty($args['input']['cart_item_id'])) {
+            throw new GraphQlInputException(__('Required parameter "cart_item_id" is missing.'));
         }
         $itemId = $args['input']['cart_item_id'];
 
         $cart = $this->getCartForUser->execute($maskedCartId, $context->getUserId());
 
         try {
-            $this->guestCartItemRepository->deleteById($maskedCartId, $itemId);
+            $this->cartItemRepository->deleteById((int)$cart->getId(), $itemId);
         } catch (NoSuchEntityException $e) {
             throw new GraphQlNoSuchEntityException(__($e->getMessage()), $e);
         } catch (LocalizedException $e) {
diff --git a/app/code/Magento/QuoteGraphQl/Model/Resolver/UpdateCartItems.php b/app/code/Magento/QuoteGraphQl/Model/Resolver/UpdateCartItems.php
new file mode 100644
index 000000000000..78a07506556c
--- /dev/null
+++ b/app/code/Magento/QuoteGraphQl/Model/Resolver/UpdateCartItems.php
@@ -0,0 +1,118 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\QuoteGraphQl\Model\Resolver;
+
+use Magento\Framework\Exception\LocalizedException;
+use Magento\Framework\Exception\NoSuchEntityException;
+use Magento\Framework\GraphQl\Config\Element\Field;
+use Magento\Framework\GraphQl\Exception\GraphQlInputException;
+use Magento\Framework\GraphQl\Exception\GraphQlNoSuchEntityException;
+use Magento\Framework\GraphQl\Query\ResolverInterface;
+use Magento\Framework\GraphQl\Schema\Type\ResolveInfo;
+use Magento\Quote\Api\CartItemRepositoryInterface;
+use Magento\Quote\Model\Quote;
+use Magento\QuoteGraphQl\Model\Cart\GetCartForUser;
+
+/**
+ * @inheritdoc
+ */
+class UpdateCartItems implements ResolverInterface
+{
+    /**
+     * @var GetCartForUser
+     */
+    private $getCartForUser;
+
+    /**
+     * @var CartItemRepositoryInterface
+     */
+    private $cartItemRepository;
+
+    /**
+     * @param GetCartForUser $getCartForUser
+     * @param CartItemRepositoryInterface $cartItemRepository
+     */
+    public function __construct(
+        GetCartForUser $getCartForUser,
+        CartItemRepositoryInterface $cartItemRepository
+    ) {
+        $this->getCartForUser = $getCartForUser;
+        $this->cartItemRepository = $cartItemRepository;
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function resolve(Field $field, $context, ResolveInfo $info, array $value = null, array $args = null)
+    {
+        if (!isset($args['input']['cart_id']) || empty($args['input']['cart_id'])) {
+            throw new GraphQlInputException(__('Required parameter "cart_id" is missing.'));
+        }
+        $maskedCartId = $args['input']['cart_id'];
+
+        if (!isset($args['input']['cart_items']) || empty($args['input']['cart_items'])
+            || !is_array($args['input']['cart_items'])
+        ) {
+            throw new GraphQlInputException(__('Required parameter "cart_items" is missing.'));
+        }
+        $cartItems = $args['input']['cart_items'];
+
+        $cart = $this->getCartForUser->execute($maskedCartId, $context->getUserId());
+
+        try {
+            $this->processCartItems($cart, $cartItems);
+        } catch (NoSuchEntityException $e) {
+            throw new GraphQlNoSuchEntityException(__($e->getMessage()), $e);
+        } catch (LocalizedException $e) {
+            throw new GraphQlInputException(__($e->getMessage()), $e);
+        }
+
+        return [
+            'cart' => [
+                'model' => $cart,
+            ],
+        ];
+    }
+
+    /**
+     * Process cart items
+     *
+     * @param Quote $cart
+     * @param array $items
+     * @throws GraphQlInputException
+     * @throws LocalizedException
+     */
+    private function processCartItems(Quote $cart, array $items): void
+    {
+        foreach ($items as $item) {
+            if (!isset($item['cart_item_id']) || empty($item['cart_item_id'])) {
+                throw new GraphQlInputException(__('Required parameter "cart_item_id" for "cart_items" is missing.'));
+            }
+            $itemId = $item['cart_item_id'];
+
+            if (!isset($item['quantity'])) {
+                throw new GraphQlInputException(__('Required parameter "quantity" for "cart_items" is missing.'));
+            }
+            $qty = (float)$item['quantity'];
+
+            $cartItem = $cart->getItemById($itemId);
+            if ($cartItem === false) {
+                throw new GraphQlNoSuchEntityException(
+                    __('Could not find cart item with id: %1.', $item['cart_item_id'])
+                );
+            }
+
+            if ($qty <= 0.0) {
+                $this->cartItemRepository->deleteById((int)$cart->getId(), $itemId);
+            } else {
+                $cartItem->setQty($qty);
+                $this->cartItemRepository->save($cartItem);
+            }
+        }
+    }
+}
diff --git a/app/code/Magento/QuoteGraphQl/etc/schema.graphqls b/app/code/Magento/QuoteGraphQl/etc/schema.graphqls
index 5f65a990bac2..268cac83d3d8 100644
--- a/app/code/Magento/QuoteGraphQl/etc/schema.graphqls
+++ b/app/code/Magento/QuoteGraphQl/etc/schema.graphqls
@@ -11,6 +11,7 @@ type Mutation {
     addVirtualProductsToCart(input: AddVirtualProductsToCartInput): AddVirtualProductsToCartOutput @resolver(class: "Magento\\QuoteGraphQl\\Model\\Resolver\\AddSimpleProductsToCart")
     applyCouponToCart(input: ApplyCouponToCartInput): ApplyCouponToCartOutput @resolver(class: "\\Magento\\QuoteGraphQl\\Model\\Resolver\\ApplyCouponToCart")
     removeCouponFromCart(input: RemoveCouponFromCartInput): RemoveCouponFromCartOutput @resolver(class: "\\Magento\\QuoteGraphQl\\Model\\Resolver\\RemoveCouponFromCart")
+    updateCartItems(input: UpdateCartItemsInput): UpdateCartItemsOutput @resolver(class: "Magento\\QuoteGraphQl\\Model\\Resolver\\UpdateCartItems")
     removeItemFromCart(input: RemoveItemFromCartInput): RemoveItemFromCartOutput @resolver(class: "Magento\\QuoteGraphQl\\Model\\Resolver\\RemoveItemFromCart")
     setShippingAddressesOnCart(input: SetShippingAddressesOnCartInput): SetShippingAddressesOnCartOutput @resolver(class: "\\Magento\\QuoteGraphQl\\Model\\Resolver\\SetShippingAddressesOnCart")
     setBillingAddressOnCart(input: SetBillingAddressOnCartInput): SetBillingAddressOnCartOutput @resolver(class: "\\Magento\\QuoteGraphQl\\Model\\Resolver\\SetBillingAddressOnCart")
@@ -53,6 +54,11 @@ input ApplyCouponToCartInput {
     coupon_code: String!
 }
 
+input UpdateCartItemsInput {
+    cart_id: String!
+    cart_items: [CartItemQuantityInput!]!
+}
+
 input RemoveItemFromCartInput {
     cart_id: String!
     cart_item_id: Int!
@@ -230,6 +236,10 @@ type AddVirtualProductsToCartOutput {
     cart: Cart!
 }
 
+type UpdateCartItemsOutput {
+    cart: Cart!
+}
+
 type RemoveItemFromCartOutput {
     cart: Cart!
 }
diff --git a/dev/tests/api-functional/testsuite/Magento/GraphQl/Quote/Customer/RemoveItemFromCartTest.php b/dev/tests/api-functional/testsuite/Magento/GraphQl/Quote/Customer/RemoveItemFromCartTest.php
index a351a2188a66..dc2807843682 100644
--- a/dev/tests/api-functional/testsuite/Magento/GraphQl/Quote/Customer/RemoveItemFromCartTest.php
+++ b/dev/tests/api-functional/testsuite/Magento/GraphQl/Quote/Customer/RemoveItemFromCartTest.php
@@ -75,20 +75,24 @@ public function testRemoveItemFromCart()
 
     /**
      * @magentoApiDataFixture Magento/Customer/_files/customer.php
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_simple_product_saved.php
      * @expectedException \Exception
      * @expectedExceptionMessage Could not find a cart with ID "non_existent_masked_id"
      */
     public function testRemoveItemFromNonExistentCart()
     {
-        $query = $this->prepareMutationQuery('non_existent_masked_id', 1);
+        $quote = $this->quoteFactory->create();
+        $this->quoteResource->load($quote, 'test_order_1', 'reserved_order_id');
+        $itemId = (int)$quote->getItemByProduct($this->productRepository->get('simple'))->getId();
 
+        $query = $this->prepareMutationQuery('non_existent_masked_id', $itemId);
         $this->graphQlQuery($query, [], '', $this->getHeaderMap());
     }
 
     /**
      * @magentoApiDataFixture Magento/Checkout/_files/quote_with_address_saved.php
      */
-    public function testRemoveNotExistentItem()
+    public function testRemoveNonExistentItem()
     {
         $quote = $this->quoteFactory->create();
         $this->quoteResource->load($quote, 'test_order_1', 'reserved_order_id');
@@ -183,6 +187,50 @@ public function testRemoveItemFromAnotherCustomerCart()
         $this->graphQlQuery($query, [], '', $this->getHeaderMap());
     }
 
+    /**
+     * @magentoApiDataFixture Magento/Customer/_files/customer.php
+     * @param string $input
+     * @param string $message
+     * @dataProvider dataProviderUpdateWithMissedRequiredParameters
+     */
+    public function testUpdateWithMissedItemRequiredParameters(string $input, string $message)
+    {
+        $query = <<<QUERY
+mutation {
+  removeItemFromCart(
+    input: {
+      {$input}
+    }
+  ) {
+    cart {
+      items {
+        qty
+      }
+    }
+  }
+}
+QUERY;
+        $this->expectExceptionMessage($message);
+        $this->graphQlQuery($query, [], '', $this->getHeaderMap());
+    }
+
+    /**
+     * @return array
+     */
+    public function dataProviderUpdateWithMissedRequiredParameters(): array
+    {
+        return [
+            'missed_cart_id' => [
+                'cart_item_id: 1',
+                'Required parameter "cart_id" is missing.'
+            ],
+            'missed_cart_item_id' => [
+                'cart_id: "test"',
+                'Required parameter "cart_item_id" is missing.'
+            ],
+        ];
+    }
+
     /**
      * @param string $maskedQuoteId
      * @param int $itemId
diff --git a/dev/tests/api-functional/testsuite/Magento/GraphQl/Quote/Customer/UpdateCartItemsTest.php b/dev/tests/api-functional/testsuite/Magento/GraphQl/Quote/Customer/UpdateCartItemsTest.php
new file mode 100644
index 000000000000..ea08d65f8ae0
--- /dev/null
+++ b/dev/tests/api-functional/testsuite/Magento/GraphQl/Quote/Customer/UpdateCartItemsTest.php
@@ -0,0 +1,339 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\GraphQl\Quote\Customer;
+
+use Magento\Catalog\Api\ProductRepositoryInterface;
+use Magento\Integration\Api\CustomerTokenServiceInterface;
+use Magento\Quote\Model\QuoteFactory;
+use Magento\Quote\Model\QuoteIdToMaskedQuoteIdInterface;
+use Magento\Quote\Model\ResourceModel\Quote as QuoteResource;
+use Magento\TestFramework\Helper\Bootstrap;
+use Magento\TestFramework\TestCase\GraphQlAbstract;
+
+/**
+ * Test for updating shopping cart items
+ */
+class UpdateCartItemsTest extends GraphQlAbstract
+{
+    /**
+     * @var CustomerTokenServiceInterface
+     */
+    private $customerTokenService;
+
+    /**
+     * @var QuoteResource
+     */
+    private $quoteResource;
+
+    /**
+     * @var QuoteFactory
+     */
+    private $quoteFactory;
+
+    /**
+     * @var QuoteIdToMaskedQuoteIdInterface
+     */
+    private $quoteIdToMaskedId;
+
+    /**
+     * @var ProductRepositoryInterface
+     */
+    private $productRepository;
+
+    protected function setUp()
+    {
+        $objectManager = Bootstrap::getObjectManager();
+        $this->quoteResource = $objectManager->get(QuoteResource::class);
+        $this->quoteFactory = $objectManager->get(QuoteFactory::class);
+        $this->quoteIdToMaskedId = $objectManager->get(QuoteIdToMaskedQuoteIdInterface::class);
+        $this->customerTokenService = $objectManager->get(CustomerTokenServiceInterface::class);
+        $this->productRepository = $objectManager->get(ProductRepositoryInterface::class);
+    }
+
+    /**
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_address_saved.php
+     */
+    public function testUpdateCartItemQty()
+    {
+        $quote = $this->quoteFactory->create();
+        $this->quoteResource->load($quote, 'test_order_1', 'reserved_order_id');
+        $maskedQuoteId = $this->quoteIdToMaskedId->execute((int)$quote->getId());
+        $itemId = (int)$quote->getItemByProduct($this->productRepository->get('simple'))->getId();
+        $qty = 2;
+
+        $query = $this->getQuery($maskedQuoteId, $itemId, $qty);
+        $response = $this->graphQlQuery($query, [], '', $this->getHeaderMap());
+
+        $this->assertArrayHasKey('updateCartItems', $response);
+        $this->assertArrayHasKey('cart', $response['updateCartItems']);
+
+        $responseCart = $response['updateCartItems']['cart'];
+        $item = current($responseCart['items']);
+
+        $this->assertEquals($itemId, $item['id']);
+        $this->assertEquals($qty, $item['qty']);
+    }
+
+    /**
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_address_saved.php
+     */
+    public function testRemoveCartItemIfQuantityIsZero()
+    {
+        $quote = $this->quoteFactory->create();
+        $this->quoteResource->load($quote, 'test_order_1', 'reserved_order_id');
+        $maskedQuoteId = $this->quoteIdToMaskedId->execute((int)$quote->getId());
+        $itemId = (int)$quote->getItemByProduct($this->productRepository->get('simple'))->getId();
+        $qty = 0;
+
+        $query = $this->getQuery($maskedQuoteId, $itemId, $qty);
+        $response = $this->graphQlQuery($query, [], '', $this->getHeaderMap());
+
+        $this->assertArrayHasKey('updateCartItems', $response);
+        $this->assertArrayHasKey('cart', $response['updateCartItems']);
+
+        $responseCart = $response['updateCartItems']['cart'];
+        $this->assertCount(0, $responseCart['items']);
+    }
+
+    /**
+     * @magentoApiDataFixture Magento/Customer/_files/customer.php
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_simple_product_saved.php
+     * @expectedException \Exception
+     * @expectedExceptionMessage Could not find a cart with ID "non_existent_masked_id"
+     */
+    public function testUpdateItemInNonExistentCart()
+    {
+        $quote = $this->quoteFactory->create();
+        $this->quoteResource->load($quote, 'test_order_with_simple_product_without_address', 'reserved_order_id');
+        $itemId = (int)$quote->getItemByProduct($this->productRepository->get('simple'))->getId();
+
+        $query = $this->getQuery('non_existent_masked_id', $itemId, 2);
+        $this->graphQlQuery($query, [], '', $this->getHeaderMap());
+    }
+
+    /**
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_address_saved.php
+     */
+    public function testUpdateNonExistentItem()
+    {
+        $quote = $this->quoteFactory->create();
+        $this->quoteResource->load($quote, 'test_order_1', 'reserved_order_id');
+        $maskedQuoteId = $this->quoteIdToMaskedId->execute((int)$quote->getId());
+        $notExistentItemId = 999;
+
+        $this->expectExceptionMessage("Could not find cart item with id: {$notExistentItemId}.");
+
+        $query = $this->getQuery($maskedQuoteId, $notExistentItemId, 2);
+        $this->graphQlQuery($query, [], '', $this->getHeaderMap());
+    }
+
+    /**
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_address_saved.php
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_virtual_product_saved.php
+     */
+    public function testUpdateItemIfItemIsNotBelongToCart()
+    {
+        $firstQuote = $this->quoteFactory->create();
+        $this->quoteResource->load($firstQuote, 'test_order_1', 'reserved_order_id');
+        $firstQuoteMaskedId = $this->quoteIdToMaskedId->execute((int)$firstQuote->getId());
+
+        $secondQuote = $this->quoteFactory->create();
+        $this->quoteResource->load(
+            $secondQuote,
+            'test_order_with_virtual_product_without_address',
+            'reserved_order_id'
+        );
+        $secondQuote->setCustomerId(1);
+        $this->quoteResource->save($secondQuote);
+        $secondQuoteItemId = (int)$secondQuote
+            ->getItemByProduct($this->productRepository->get('virtual-product'))
+            ->getId();
+
+        $this->expectExceptionMessage("Could not find cart item with id: {$secondQuoteItemId}.");
+
+        $query = $this->getQuery($firstQuoteMaskedId, $secondQuoteItemId, 2);
+        $this->graphQlQuery($query, [], '', $this->getHeaderMap());
+    }
+
+    /**
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_address_saved.php
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_virtual_product_saved.php
+     */
+    public function testUpdateItemInGuestCart()
+    {
+        $guestQuote = $this->quoteFactory->create();
+        $this->quoteResource->load(
+            $guestQuote,
+            'test_order_with_virtual_product_without_address',
+            'reserved_order_id'
+        );
+        $guestQuoteMaskedId = $this->quoteIdToMaskedId->execute((int)$guestQuote->getId());
+        $guestQuoteItemId = (int)$guestQuote
+            ->getItemByProduct($this->productRepository->get('virtual-product'))
+            ->getId();
+
+        $this->expectExceptionMessage(
+            "The current user cannot perform operations on cart \"$guestQuoteMaskedId\""
+        );
+
+        $query = $this->getQuery($guestQuoteMaskedId, $guestQuoteItemId, 2);
+        $this->graphQlQuery($query, [], '', $this->getHeaderMap());
+    }
+
+    /**
+     * @magentoApiDataFixture Magento/Customer/_files/three_customers.php
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_address_saved.php
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_virtual_product_saved.php
+     */
+    public function testUpdateItemInAnotherCustomerCart()
+    {
+        $anotherCustomerQuote = $this->quoteFactory->create();
+        $this->quoteResource->load(
+            $anotherCustomerQuote,
+            'test_order_with_virtual_product_without_address',
+            'reserved_order_id'
+        );
+        $anotherCustomerQuote->setCustomerId(2);
+        $this->quoteResource->save($anotherCustomerQuote);
+
+        $anotherCustomerQuoteMaskedId = $this->quoteIdToMaskedId->execute((int)$anotherCustomerQuote->getId());
+        $anotherCustomerQuoteItemId = (int)$anotherCustomerQuote
+            ->getItemByProduct($this->productRepository->get('virtual-product'))
+            ->getId();
+
+        $this->expectExceptionMessage(
+            "The current user cannot perform operations on cart \"$anotherCustomerQuoteMaskedId\""
+        );
+
+        $query = $this->getQuery($anotherCustomerQuoteMaskedId, $anotherCustomerQuoteItemId, 2);
+        $this->graphQlQuery($query, [], '', $this->getHeaderMap());
+    }
+
+    /**
+     * @magentoApiDataFixture Magento/Customer/_files/customer.php
+     * @expectedException \Exception
+     * @expectedExceptionMessage Required parameter "cart_id" is missing.
+     */
+    public function testUpdateWithMissedCartItemId()
+    {
+        $query = <<<QUERY
+mutation {
+  updateCartItems(input: {
+    cart_items: [
+      {
+        cart_item_id: 1
+        quantity: 2
+      }
+    ]  
+  }) {
+    cart {
+      items {
+        id
+        qty
+      }
+    }
+  }
+}
+QUERY;
+        $this->graphQlQuery($query, [], '', $this->getHeaderMap());
+    }
+
+    /**
+     * @param string $input
+     * @param string $message
+     * @dataProvider dataProviderUpdateWithMissedRequiredParameters
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_address_saved.php
+     */
+    public function testUpdateWithMissedItemRequiredParameters(string $input, string $message)
+    {
+        $quote = $this->quoteFactory->create();
+        $this->quoteResource->load($quote, 'test_order_1', 'reserved_order_id');
+        $maskedQuoteId = $this->quoteIdToMaskedId->execute((int)$quote->getId());
+
+        $query = <<<QUERY
+mutation {
+  updateCartItems(input: {
+    cart_id: "{$maskedQuoteId}"
+    {$input}
+  }) {
+    cart {
+      items {
+        id
+        qty
+      }
+    }
+  }
+}
+QUERY;
+        $this->expectExceptionMessage($message);
+        $this->graphQlQuery($query, [], '', $this->getHeaderMap());
+    }
+
+    /**
+     * @return array
+     */
+    public function dataProviderUpdateWithMissedRequiredParameters(): array
+    {
+        return [
+            'missed_cart_items' => [
+                '',
+                'Required parameter "cart_items" is missing.'
+            ],
+            'missed_cart_item_id' => [
+                'cart_items: [{ quantity: 2 }]',
+                'Required parameter "cart_item_id" for "cart_items" is missing.'
+            ],
+            'missed_cart_item_qty' => [
+                'cart_items: [{ cart_item_id: 1 }]',
+                'Required parameter "quantity" for "cart_items" is missing.'
+            ],
+        ];
+    }
+
+    /**
+     * @param string $maskedQuoteId
+     * @param int $itemId
+     * @param float $qty
+     * @return string
+     */
+    private function getQuery(string $maskedQuoteId, int $itemId, float $qty): string
+    {
+        return <<<QUERY
+mutation {
+  updateCartItems(input: {
+    cart_id: "{$maskedQuoteId}"
+    cart_items:[
+      {
+        cart_item_id: {$itemId}
+        quantity: {$qty}
+      }
+    ]
+  }) {
+    cart {
+      items {
+        id
+        qty
+      }
+    }
+  }
+}
+QUERY;
+    }
+
+    /**
+     * @param string $username
+     * @param string $password
+     * @return array
+     */
+    private function getHeaderMap(string $username = 'customer@example.com', string $password = 'password'): array
+    {
+        $customerToken = $this->customerTokenService->createCustomerAccessToken($username, $password);
+        $headerMap = ['Authorization' => 'Bearer ' . $customerToken];
+        return $headerMap;
+    }
+}
diff --git a/dev/tests/api-functional/testsuite/Magento/GraphQl/Quote/Guest/RemoveItemFromCartTest.php b/dev/tests/api-functional/testsuite/Magento/GraphQl/Quote/Guest/RemoveItemFromCartTest.php
index a6b8f05fc083..d7dc07241e21 100644
--- a/dev/tests/api-functional/testsuite/Magento/GraphQl/Quote/Guest/RemoveItemFromCartTest.php
+++ b/dev/tests/api-functional/testsuite/Magento/GraphQl/Quote/Guest/RemoveItemFromCartTest.php
@@ -67,20 +67,24 @@ public function testRemoveItemFromCart()
     }
 
     /**
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_simple_product_saved.php
      * @expectedException \Exception
      * @expectedExceptionMessage Could not find a cart with ID "non_existent_masked_id"
      */
     public function testRemoveItemFromNonExistentCart()
     {
-        $query = $this->prepareMutationQuery('non_existent_masked_id', 1);
+        $quote = $this->quoteFactory->create();
+        $this->quoteResource->load($quote, 'test_order_with_simple_product_without_address', 'reserved_order_id');
+        $itemId = (int)$quote->getItemByProduct($this->productRepository->get('simple'))->getId();
 
+        $query = $this->prepareMutationQuery('non_existent_masked_id', $itemId);
         $this->graphQlQuery($query);
     }
 
     /**
      * @magentoApiDataFixture Magento/Checkout/_files/quote_with_simple_product_saved.php
      */
-    public function testRemoveNotExistentItem()
+    public function testRemoveNonExistentItem()
     {
         $quote = $this->quoteFactory->create();
         $this->quoteResource->load($quote, 'test_order_with_simple_product_without_address', 'reserved_order_id');
@@ -139,6 +143,49 @@ public function testRemoveItemFromCustomerCart()
         $this->graphQlQuery($query);
     }
 
+    /**
+     * @param string $input
+     * @param string $message
+     * @dataProvider dataProviderUpdateWithMissedRequiredParameters
+     */
+    public function testUpdateWithMissedItemRequiredParameters(string $input, string $message)
+    {
+        $query = <<<QUERY
+mutation {
+  removeItemFromCart(
+    input: {
+      {$input}
+    }
+  ) {
+    cart {
+      items {
+        qty
+      }
+    }
+  }
+}
+QUERY;
+        $this->expectExceptionMessage($message);
+        $this->graphQlQuery($query);
+    }
+
+    /**
+     * @return array
+     */
+    public function dataProviderUpdateWithMissedRequiredParameters(): array
+    {
+        return [
+            'missed_cart_id' => [
+                'cart_item_id: 1',
+                'Required parameter "cart_id" is missing.'
+            ],
+            'missed_cart_item_id' => [
+                'cart_id: "test"',
+                'Required parameter "cart_item_id" is missing.'
+            ],
+        ];
+    }
+
     /**
      * @param string $maskedQuoteId
      * @param int $itemId
diff --git a/dev/tests/api-functional/testsuite/Magento/GraphQl/Quote/Guest/UpdateCartItemsTest.php b/dev/tests/api-functional/testsuite/Magento/GraphQl/Quote/Guest/UpdateCartItemsTest.php
new file mode 100644
index 000000000000..39e5152d43df
--- /dev/null
+++ b/dev/tests/api-functional/testsuite/Magento/GraphQl/Quote/Guest/UpdateCartItemsTest.php
@@ -0,0 +1,278 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\GraphQl\Quote\Guest;
+
+use Magento\Quote\Model\QuoteFactory;
+use Magento\Catalog\Api\ProductRepositoryInterface;
+use Magento\Quote\Model\QuoteIdToMaskedQuoteIdInterface;
+use Magento\Quote\Model\ResourceModel\Quote as QuoteResource;
+use Magento\TestFramework\Helper\Bootstrap;
+use Magento\TestFramework\TestCase\GraphQlAbstract;
+
+/**
+ * Test for updating/removing shopping cart items
+ */
+class UpdateCartItemsTest extends GraphQlAbstract
+{
+    /**
+     * @var QuoteResource
+     */
+    private $quoteResource;
+
+    /**
+     * @var QuoteFactory
+     */
+    private $quoteFactory;
+
+    /**
+     * @var QuoteIdToMaskedQuoteIdInterface
+     */
+    private $quoteIdToMaskedId;
+
+    /**
+     * @var ProductRepositoryInterface
+     */
+    private $productRepository;
+
+    protected function setUp()
+    {
+        $objectManager = Bootstrap::getObjectManager();
+        $this->quoteResource = $objectManager->get(QuoteResource::class);
+        $this->quoteFactory = $objectManager->get(QuoteFactory::class);
+        $this->quoteIdToMaskedId = $objectManager->get(QuoteIdToMaskedQuoteIdInterface::class);
+        $this->productRepository = $objectManager->get(ProductRepositoryInterface::class);
+    }
+
+    /**
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_simple_product_saved.php
+     */
+    public function testUpdateCartItemQty()
+    {
+        $quote = $this->quoteFactory->create();
+        $this->quoteResource->load($quote, 'test_order_with_simple_product_without_address', 'reserved_order_id');
+        $maskedQuoteId = $this->quoteIdToMaskedId->execute((int)$quote->getId());
+        $itemId = (int)$quote->getItemByProduct($this->productRepository->get('simple'))->getId();
+        $qty = 2;
+
+        $query = $this->getQuery($maskedQuoteId, $itemId, $qty);
+        $response = $this->graphQlQuery($query);
+
+        $this->assertArrayHasKey('updateCartItems', $response);
+        $this->assertArrayHasKey('cart', $response['updateCartItems']);
+
+        $responseCart = $response['updateCartItems']['cart'];
+        $item = current($responseCart['items']);
+
+        $this->assertEquals($itemId, $item['id']);
+        $this->assertEquals($qty, $item['qty']);
+    }
+
+    /**
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_simple_product_saved.php
+     */
+    public function testRemoveCartItemIfQuantityIsZero()
+    {
+        $quote = $this->quoteFactory->create();
+        $this->quoteResource->load($quote, 'test_order_with_simple_product_without_address', 'reserved_order_id');
+        $maskedQuoteId = $this->quoteIdToMaskedId->execute((int)$quote->getId());
+        $itemId = (int)$quote->getItemByProduct($this->productRepository->get('simple'))->getId();
+        $qty = 0;
+
+        $query = $this->getQuery($maskedQuoteId, $itemId, $qty);
+        $response = $this->graphQlQuery($query);
+
+        $this->assertArrayHasKey('updateCartItems', $response);
+        $this->assertArrayHasKey('cart', $response['updateCartItems']);
+
+        $responseCart = $response['updateCartItems']['cart'];
+        $this->assertCount(0, $responseCart['items']);
+    }
+
+    /**
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_simple_product_saved.php
+     * @expectedException \Exception
+     * @expectedExceptionMessage Could not find a cart with ID "non_existent_masked_id"
+     */
+    public function testUpdateItemInNonExistentCart()
+    {
+        $quote = $this->quoteFactory->create();
+        $this->quoteResource->load($quote, 'test_order_with_simple_product_without_address', 'reserved_order_id');
+        $itemId = (int)$quote->getItemByProduct($this->productRepository->get('simple'))->getId();
+
+        $query = $this->getQuery('non_existent_masked_id', $itemId, 2);
+        $this->graphQlQuery($query);
+    }
+
+    /**
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_simple_product_saved.php
+     */
+    public function testUpdateNonExistentItem()
+    {
+        $quote = $this->quoteFactory->create();
+        $this->quoteResource->load($quote, 'test_order_with_simple_product_without_address', 'reserved_order_id');
+        $maskedQuoteId = $this->quoteIdToMaskedId->execute((int)$quote->getId());
+        $notExistentItemId = 999;
+
+        $this->expectExceptionMessage("Could not find cart item with id: {$notExistentItemId}.");
+
+        $query = $this->getQuery($maskedQuoteId, $notExistentItemId, 2);
+        $this->graphQlQuery($query);
+    }
+
+    /**
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_simple_product_saved.php
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_virtual_product_saved.php
+     */
+    public function testUpdateItemIfItemIsNotBelongToCart()
+    {
+        $firstQuote = $this->quoteFactory->create();
+        $this->quoteResource->load($firstQuote, 'test_order_with_simple_product_without_address', 'reserved_order_id');
+        $firstQuoteMaskedId = $this->quoteIdToMaskedId->execute((int)$firstQuote->getId());
+
+        $secondQuote = $this->quoteFactory->create();
+        $this->quoteResource->load(
+            $secondQuote,
+            'test_order_with_virtual_product_without_address',
+            'reserved_order_id'
+        );
+        $secondQuoteItemId = (int)$secondQuote
+            ->getItemByProduct($this->productRepository->get('virtual-product'))
+            ->getId();
+
+        $this->expectExceptionMessage("Could not find cart item with id: {$secondQuoteItemId}.");
+
+        $query = $this->getQuery($firstQuoteMaskedId, $secondQuoteItemId, 2);
+        $this->graphQlQuery($query);
+    }
+
+    /**
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_address_saved.php
+     */
+    public function testUpdateItemFromCustomerCart()
+    {
+        $customerQuote = $this->quoteFactory->create();
+        $this->quoteResource->load($customerQuote, 'test_order_1', 'reserved_order_id');
+        $customerQuoteMaskedId = $this->quoteIdToMaskedId->execute((int)$customerQuote->getId());
+        $customerQuoteItemId = (int)$customerQuote->getItemByProduct($this->productRepository->get('simple'))->getId();
+
+        $this->expectExceptionMessage("The current user cannot perform operations on cart \"$customerQuoteMaskedId\"");
+
+        $query = $this->getQuery($customerQuoteMaskedId, $customerQuoteItemId, 2);
+        $this->graphQlQuery($query);
+    }
+
+    /**
+     * @expectedException \Exception
+     * @expectedExceptionMessage Required parameter "cart_id" is missing.
+     */
+    public function testUpdateWithMissedCartItemId()
+    {
+        $query = <<<QUERY
+mutation {
+  updateCartItems(input: {
+    cart_items: [
+      {
+        cart_item_id: 1
+        quantity: 2
+      }
+    ]  
+  }) {
+    cart {
+      items {
+        id
+        qty
+      }
+    }
+  }
+}
+QUERY;
+        $this->graphQlQuery($query);
+    }
+
+    /**
+     * @param string $input
+     * @param string $message
+     * @dataProvider dataProviderUpdateWithMissedRequiredParameters
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_simple_product_saved.php
+     */
+    public function testUpdateWithMissedItemRequiredParameters(string $input, string $message)
+    {
+        $quote = $this->quoteFactory->create();
+        $this->quoteResource->load($quote, 'test_order_with_simple_product_without_address', 'reserved_order_id');
+        $maskedQuoteId = $this->quoteIdToMaskedId->execute((int)$quote->getId());
+
+        $query = <<<QUERY
+mutation {
+  updateCartItems(input: {
+    cart_id: "{$maskedQuoteId}"
+    {$input}
+  }) {
+    cart {
+      items {
+        id
+        qty
+      }
+    }
+  }
+}
+QUERY;
+        $this->expectExceptionMessage($message);
+        $this->graphQlQuery($query);
+    }
+
+    /**
+     * @return array
+     */
+    public function dataProviderUpdateWithMissedRequiredParameters(): array
+    {
+        return [
+            'missed_cart_items' => [
+                '',
+                'Required parameter "cart_items" is missing.'
+            ],
+            'missed_cart_item_id' => [
+                'cart_items: [{ quantity: 2 }]',
+                'Required parameter "cart_item_id" for "cart_items" is missing.'
+            ],
+            'missed_cart_item_qty' => [
+                'cart_items: [{ cart_item_id: 1 }]',
+                'Required parameter "quantity" for "cart_items" is missing.'
+            ],
+        ];
+    }
+
+    /**
+     * @param string $maskedQuoteId
+     * @param int $itemId
+     * @param float $qty
+     * @return string
+     */
+    private function getQuery(string $maskedQuoteId, int $itemId, float $qty): string
+    {
+        return <<<QUERY
+mutation {
+  updateCartItems(input: {
+    cart_id: "{$maskedQuoteId}"
+    cart_items: [
+      {
+        cart_item_id: {$itemId}
+        quantity: {$qty}
+      }
+    ]
+  }) {
+    cart {
+      items {
+        id
+        qty
+      }
+    }
+  }
+}
+QUERY;
+    }
+}