diff --git a/moto/awslambda/responses.py b/moto/awslambda/responses.py
index 8ba86f8bc..f965ad2e0 100644
--- a/moto/awslambda/responses.py
+++ b/moto/awslambda/responses.py
@@ -209,6 +209,7 @@ class LambdaResponse(BaseResponse):
             function_name, qualifier, self.body, self.headers, response_headers
         )
         if payload:
+            response_headers["content-type"] = "application/json"
             if request.headers.get("X-Amz-Invocation-Type") == "Event":
                 status_code = 202
             elif request.headers.get("X-Amz-Invocation-Type") == "DryRun":
diff --git a/tests/test_awslambda/test_lambda.py b/tests/test_awslambda/test_lambda.py
index d2949aea4..fa02e282d 100644
--- a/tests/test_awslambda/test_lambda.py
+++ b/tests/test_awslambda/test_lambda.py
@@ -157,6 +157,9 @@ def test_invoke_requestresponse_function(invocation_type):
         assert False, success_result["Payload"].read().decode("utf-8")
 
     success_result["StatusCode"].should.equal(200)
+    success_result["ResponseMetadata"]["HTTPHeaders"]["content-type"].should.equal(
+        "application/json"
+    )
     logs = base64.b64decode(success_result["LogResult"]).decode("utf-8")
 
     logs.should.contain("START RequestId:")
@@ -172,6 +175,9 @@ def test_invoke_requestresponse_function(invocation_type):
     )
 
     success_result["StatusCode"].should.equal(200)
+    success_result["ResponseMetadata"]["HTTPHeaders"]["content-type"].should.equal(
+        "application/json"
+    )
     assert "LogResult" not in success_result