diff --git a/velox/expression/FunctionSignature.cpp b/velox/expression/FunctionSignature.cpp
index a1460f1355a94..5cd38fd8050f0 100644
--- a/velox/expression/FunctionSignature.cpp
+++ b/velox/expression/FunctionSignature.cpp
@@ -120,7 +120,8 @@ void validateBaseTypeAndCollectTypeParams(
 
     if (!isPositiveInteger(typeName) &&
         !tryMapNameToTypeKind(typeName).has_value() &&
-        !isDecimalName(typeName) && !isDateName(typeName)) {
+        !isDecimalName(typeName) && !isDateName(typeName) &&
+        typeName != "JSON") {
       VELOX_USER_CHECK(hasType(typeName), "Type doesn't exist: '{}'", typeName);
     }
 
diff --git a/velox/functions/prestosql/aggregates/ApproxMostFrequentAggregate.cpp b/velox/functions/prestosql/aggregates/ApproxMostFrequentAggregate.cpp
index 35f9af9e38866..2a6dfd65d2685 100644
--- a/velox/functions/prestosql/aggregates/ApproxMostFrequentAggregate.cpp
+++ b/velox/functions/prestosql/aggregates/ApproxMostFrequentAggregate.cpp
@@ -477,7 +477,13 @@ void registerApproxMostFrequentAggregate(
     bool overwrite) {
   std::vector<std::shared_ptr<exec::AggregateFunctionSignature>> signatures;
   for (const auto& valueType :
-       {"boolean", "tinyint", "smallint", "integer", "bigint", "varchar"}) {
+       {"boolean",
+        "tinyint",
+        "smallint",
+        "integer",
+        "bigint",
+        "varchar",
+        "json"}) {
     signatures.push_back(
         exec::AggregateFunctionSignatureBuilder()
             .returnType(fmt::format("map({},bigint)", valueType))
diff --git a/velox/functions/prestosql/aggregates/tests/ApproxMostFrequentTest.cpp b/velox/functions/prestosql/aggregates/tests/ApproxMostFrequentTest.cpp
index 148357159c255..bf9932d4292a0 100644
--- a/velox/functions/prestosql/aggregates/tests/ApproxMostFrequentTest.cpp
+++ b/velox/functions/prestosql/aggregates/tests/ApproxMostFrequentTest.cpp
@@ -281,5 +281,38 @@ TEST_F(ApproxMostFrequentTestBoolean, basic) {
       {input}, {"c0"}, {"approx_most_frequent(3, c5, 31)"}, {expected});
 }
 
+class ApproxMostFrequentTestJson : public AggregationTestBase {
+ protected:
+  void SetUp() override {
+    AggregationTestBase::SetUp();
+  }
+};
+
+TEST_F(ApproxMostFrequentTestJson, basic) {
+  // JSON strings as input
+  std::vector<std::string> jsonStrings = {
+      "{\"type\": \"store\"}",
+      "{\"type\": \"fruit\"}",
+      "{\"type\": \"fruit\"}",
+      "{\"type\": \"book\"}",
+      "{\"type\": \"store\"}",
+      "{\"type\": \"fruit\"}"};
+
+  auto inputVector = makeFlatVector<StringView>(
+      static_cast<vector_size_t>(jsonStrings.size()),
+      [&](auto row) { return StringView(jsonStrings[row]); });
+
+  MapVectorPtr expectedMap = makeMapVector<StringView, int64_t>(
+      {{{StringView("{\"type\": \"fruit\"}"), 3},
+        {StringView("{\"type\": \"store\"}"), 2}}});
+  auto expected = makeRowVector({{expectedMap}});
+
+  testAggregations(
+      {makeRowVector({inputVector})},
+      {},
+      {"approx_most_frequent(2, c0, 31)"},
+      {expected});
+}
+
 } // namespace
 } // namespace facebook::velox::aggregate::test
diff --git a/velox/functions/prestosql/fuzzer/AggregationFuzzerTest.cpp b/velox/functions/prestosql/fuzzer/AggregationFuzzerTest.cpp
index f9c205c5ab68e..446cf9d3c69c6 100644
--- a/velox/functions/prestosql/fuzzer/AggregationFuzzerTest.cpp
+++ b/velox/functions/prestosql/fuzzer/AggregationFuzzerTest.cpp
@@ -35,6 +35,7 @@
 #include "velox/functions/prestosql/fuzzer/MinMaxByResultVerifier.h"
 #include "velox/functions/prestosql/fuzzer/MinMaxInputGenerator.h"
 #include "velox/functions/prestosql/registration/RegistrationFunctions.h"
+#include "velox/functions/prestosql/types/JsonType.h"
 #include "velox/functions/prestosql/window/WindowFunctionsRegistration.h"
 #include "velox/vector/fuzzer/VectorFuzzer.h"
 
@@ -101,6 +102,7 @@ int main(int argc, char** argv) {
   // experience, and initialize glog and gflags.
   folly::Init init(&argc, &argv);
 
+  facebook::velox::registerJsonType();
   // Register only presto supported signatures if we are verifying against
   // Presto.
   if (FLAGS_presto_url.empty()) {
diff --git a/velox/functions/prestosql/fuzzer/WindowFuzzerTest.cpp b/velox/functions/prestosql/fuzzer/WindowFuzzerTest.cpp
index 6453df359af87..e8a29a6c80238 100644
--- a/velox/functions/prestosql/fuzzer/WindowFuzzerTest.cpp
+++ b/velox/functions/prestosql/fuzzer/WindowFuzzerTest.cpp
@@ -30,6 +30,7 @@
 #include "velox/functions/prestosql/fuzzer/MinMaxInputGenerator.h"
 #include "velox/functions/prestosql/fuzzer/WindowOffsetInputGenerator.h"
 #include "velox/functions/prestosql/registration/RegistrationFunctions.h"
+#include "velox/functions/prestosql/types/JsonType.h"
 #include "velox/functions/prestosql/window/WindowFunctionsRegistration.h"
 #include "velox/vector/fuzzer/VectorFuzzer.h"
 
@@ -92,6 +93,7 @@ getCustomInputGenerators() {
 } // namespace facebook::velox::exec::test
 
 int main(int argc, char** argv) {
+  facebook::velox::registerJsonType();
   facebook::velox::aggregate::prestosql::registerAllAggregateFunctions(
       "", false, true);
   facebook::velox::aggregate::prestosql::registerInternalAggregateFunctions("");