diff --git a/moto/ecs/models.py b/moto/ecs/models.py
index 850516ae4..863275ab4 100644
--- a/moto/ecs/models.py
+++ b/moto/ecs/models.py
@@ -129,6 +129,8 @@ class TaskDefinition(BaseObject, CloudFormationModel):
         requires_compatibilities=None,
         cpu=None,
         memory=None,
+        task_role_arn=None,
+        execution_role_arn=None,
     ):
         self.family = family
         self.revision = revision
@@ -169,6 +171,11 @@ class TaskDefinition(BaseObject, CloudFormationModel):
         else:
             self.network_mode = network_mode
 
+        if task_role_arn is not None:
+            self.task_role_arn = task_role_arn
+        if execution_role_arn is not None:
+            self.execution_role_arn = execution_role_arn
+
         self.placement_constraints = (
             placement_constraints if placement_constraints is not None else []
         )
@@ -737,6 +744,8 @@ class EC2ContainerServiceBackend(BaseBackend):
         requires_compatibilities=None,
         cpu=None,
         memory=None,
+        task_role_arn=None,
+        execution_role_arn=None,
     ):
         if family in self.task_definitions:
             last_id = self._get_last_task_definition_revision_id(family)
@@ -756,6 +765,8 @@ class EC2ContainerServiceBackend(BaseBackend):
             requires_compatibilities=requires_compatibilities,
             cpu=cpu,
             memory=memory,
+            task_role_arn=task_role_arn,
+            execution_role_arn=execution_role_arn,
         )
         self.task_definitions[family][revision] = task_definition
 
diff --git a/moto/ecs/responses.py b/moto/ecs/responses.py
index 03b8b2618..3fed25ecd 100644
--- a/moto/ecs/responses.py
+++ b/moto/ecs/responses.py
@@ -67,6 +67,9 @@ class EC2ContainerServiceResponse(BaseResponse):
         requires_compatibilities = self._get_param("requiresCompatibilities")
         cpu = self._get_param("cpu")
         memory = self._get_param("memory")
+        task_role_arn = self._get_param("taskRoleArn")
+        execution_role_arn = self._get_param("executionRoleArn")
+
         task_definition = self.ecs_backend.register_task_definition(
             family,
             container_definitions,
@@ -77,6 +80,8 @@ class EC2ContainerServiceResponse(BaseResponse):
             requires_compatibilities=requires_compatibilities,
             cpu=cpu,
             memory=memory,
+            task_role_arn=task_role_arn,
+            execution_role_arn=execution_role_arn,
         )
         return json.dumps({"taskDefinition": task_definition.response_object})
 
diff --git a/tests/test_ecs/test_ecs_boto3.py b/tests/test_ecs/test_ecs_boto3.py
index 47a5b00bd..9d130ba83 100644
--- a/tests/test_ecs/test_ecs_boto3.py
+++ b/tests/test_ecs/test_ecs_boto3.py
@@ -151,10 +151,16 @@ def test_register_task_definition():
 
     # Registering with optional top-level params
     definition["requiresCompatibilities"] = ["FARGATE"]
+    definition["taskRoleArn"] = "my-custom-task-role-arn"
+    definition["executionRoleArn"] = "my-custom-execution-role-arn"
     response = client.register_task_definition(**definition)
     response["taskDefinition"]["requiresCompatibilities"].should.equal(["FARGATE"])
     response["taskDefinition"]["compatibilities"].should.equal(["EC2", "FARGATE"])
     response["taskDefinition"]["networkMode"].should.equal("awsvpc")
+    response["taskDefinition"]["taskRoleArn"].should.equal("my-custom-task-role-arn")
+    response["taskDefinition"]["executionRoleArn"].should.equal(
+        "my-custom-execution-role-arn"
+    )
 
     definition["requiresCompatibilities"] = ["EC2", "FARGATE"]
     response = client.register_task_definition(**definition)
@@ -333,6 +339,8 @@ def test_describe_task_definitions():
     )
     _ = client.register_task_definition(
         family="test_ecs_task",
+        taskRoleArn="my-task-role-arn",
+        executionRoleArn="my-execution-role-arn",
         containerDefinitions=[
             {
                 "name": "hello_world2",
@@ -372,6 +380,8 @@ def test_describe_task_definitions():
     response["taskDefinition"]["taskDefinitionArn"].should.equal(
         "arn:aws:ecs:us-east-1:{}:task-definition/test_ecs_task:2".format(ACCOUNT_ID)
     )
+    response["taskDefinition"]["taskRoleArn"].should.equal("my-task-role-arn")
+    response["taskDefinition"]["executionRoleArn"].should.equal("my-execution-role-arn")
 
     response = client.describe_task_definition(
         taskDefinition="test_ecs_task:1", include=["TAGS"]