diff --git a/CHANGELOG.md b/CHANGELOG.md
index 113597cb7aa9..0d01901e725b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -114,6 +114,8 @@
   either the truncated coins or the change coins.
 * [\#3915](https://github.com/cosmos/cosmos-sdk/issues/3915) Remove ';' delimiting support from ParseDecCoins
 * [\#3977](https://github.com/cosmos/cosmos-sdk/issues/3977) Fix docker image build
+* [\#4020](https://github.com/cosmos/cosmos-sdk/issues/4020) Fix queryDelegationRewards by returning an error
+when the validator or delegation do not exist.
 
 ## 0.33.2
 
diff --git a/x/distribution/keeper/querier.go b/x/distribution/keeper/querier.go
index ac40700c52f1..984bb744824a 100644
--- a/x/distribution/keeper/querier.go
+++ b/x/distribution/keeper/querier.go
@@ -207,7 +207,17 @@ func queryDelegationRewards(ctx sdk.Context, _ []string, req abci.RequestQuery,
 	ctx, _ = ctx.CacheContext()
 
 	val := k.stakingKeeper.Validator(ctx, params.ValidatorAddress)
+	if val == nil {
+		// TODO: Should use ErrNoValidatorFound from staking/types
+		return nil, sdk.ErrInternal(fmt.Sprintf("validator %s does not exist", params.ValidatorAddress))
+	}
+
 	del := k.stakingKeeper.Delegation(ctx, params.DelegatorAddress, params.ValidatorAddress)
+	if del == nil {
+		// TODO: Should use ErrNoDelegation from staking/types
+		return nil, sdk.ErrInternal("delegation does not exist")
+	}
+
 	endingPeriod := k.incrementValidatorPeriod(ctx, val)
 	rewards := k.calculateDelegationRewards(ctx, val, del, endingPeriod)