diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7967e69f..f3cc4f89 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Changed `push_to_s3` deployment step function to write paths `as_posix()` to allow support for deploying from windows [#314](https://github.com/PrefectHQ/prefect-aws/pull/314)
 
+### Fixed
+
+- Resolved an issue where defining a custom network configuration with a subnet would erroneously report it as missing from the VPC when more than one subnet exists in the VPC. [#321](https://github.com/PrefectHQ/prefect-aws/pull/321)
+
 ### Deprecated
 
 ### Removed
diff --git a/prefect_aws/workers/ecs_worker.py b/prefect_aws/workers/ecs_worker.py
index 1b1c8073..a3822a3f 100644
--- a/prefect_aws/workers/ecs_worker.py
+++ b/prefect_aws/workers/ecs_worker.py
@@ -1349,10 +1349,10 @@ def _custom_network_configuration(
                 + "Network configuration cannot be inferred."
             )
 
+        subnet_ids = [subnet["SubnetId"] for subnet in subnets]
+
         config_subnets = network_configuration.get("subnets", [])
-        if not all(
-            [conf_sn in sn.values() for conf_sn in config_subnets for sn in subnets]
-        ):
+        if not all(conf_sn in subnet_ids for conf_sn in config_subnets):
             raise ValueError(
                 f"Subnets {config_subnets} not found within {vpc_message}."
                 + "Please check that VPC is associated with supplied subnets."
diff --git a/tests/workers/test_ecs_worker.py b/tests/workers/test_ecs_worker.py
index 1be6eb70..2c177aae 100644
--- a/tests/workers/test_ecs_worker.py
+++ b/tests/workers/test_ecs_worker.py
@@ -892,7 +892,7 @@ async def test_network_config_from_vpc_id(
 
 
 @pytest.mark.usefixtures("ecs_mocks")
-async def test_network_config_from_custom_settings(
+async def test_network_config_1_subnet_in_custom_settings_1_in_vpc(
     aws_credentials: AwsCredentials, flow_run: FlowRun
 ):
     session = aws_credentials.get_boto3_session()
@@ -937,6 +937,107 @@ async def test_network_config_from_custom_settings(
     }
 
 
+@pytest.mark.usefixtures("ecs_mocks")
+async def test_network_config_1_sn_in_custom_settings_many_in_vpc(
+    aws_credentials: AwsCredentials, flow_run: FlowRun
+):
+    session = aws_credentials.get_boto3_session()
+    ec2_resource = session.resource("ec2")
+    vpc = ec2_resource.create_vpc(CidrBlock="10.0.0.0/16")
+    subnet = ec2_resource.create_subnet(CidrBlock="10.0.2.0/24", VpcId=vpc.id)
+    ec2_resource.create_subnet(CidrBlock="10.0.3.0/24", VpcId=vpc.id)
+    ec2_resource.create_subnet(CidrBlock="10.0.4.0/24", VpcId=vpc.id)
+
+    security_group = ec2_resource.create_security_group(
+        GroupName="ECSWorkerTestSG", Description="ECS Worker test SG", VpcId=vpc.id
+    )
+
+    configuration = await construct_configuration(
+        aws_credentials=aws_credentials,
+        vpc_id=vpc.id,
+        override_network_configuration=True,
+        network_configuration={
+            "subnets": [subnet.id],
+            "assignPublicIp": "DISABLED",
+            "securityGroups": [security_group.id],
+        },
+    )
+
+    session = aws_credentials.get_boto3_session()
+
+    async with ECSWorker(work_pool_name="test") as worker:
+        # Capture the task run call because moto does not track 'networkConfiguration'
+        original_run_task = worker._create_task_run
+        mock_run_task = MagicMock(side_effect=original_run_task)
+        worker._create_task_run = mock_run_task
+
+        result = await run_then_stop_task(worker, configuration, flow_run)
+
+    assert result.status_code == 0
+    network_configuration = mock_run_task.call_args[0][1].get("networkConfiguration")
+
+    # Subnet ids are copied from the vpc
+    assert network_configuration == {
+        "awsvpcConfiguration": {
+            "subnets": [subnet.id],
+            "assignPublicIp": "DISABLED",
+            "securityGroups": [security_group.id],
+        }
+    }
+
+
+@pytest.mark.usefixtures("ecs_mocks")
+async def test_network_config_many_subnet_in_custom_settings_many_in_vpc(
+    aws_credentials: AwsCredentials, flow_run: FlowRun
+):
+    session = aws_credentials.get_boto3_session()
+    ec2_resource = session.resource("ec2")
+    vpc = ec2_resource.create_vpc(CidrBlock="10.0.0.0/16")
+    subnets = [
+        ec2_resource.create_subnet(CidrBlock="10.0.2.0/24", VpcId=vpc.id),
+        ec2_resource.create_subnet(CidrBlock="10.0.33.0/24", VpcId=vpc.id),
+        ec2_resource.create_subnet(CidrBlock="10.0.44.0/24", VpcId=vpc.id),
+    ]
+    subnet_ids = [subnet.id for subnet in subnets]
+
+    security_group = ec2_resource.create_security_group(
+        GroupName="ECSWorkerTestSG", Description="ECS Worker test SG", VpcId=vpc.id
+    )
+
+    configuration = await construct_configuration(
+        aws_credentials=aws_credentials,
+        vpc_id=vpc.id,
+        override_network_configuration=True,
+        network_configuration={
+            "subnets": subnet_ids,
+            "assignPublicIp": "DISABLED",
+            "securityGroups": [security_group.id],
+        },
+    )
+
+    session = aws_credentials.get_boto3_session()
+
+    async with ECSWorker(work_pool_name="test") as worker:
+        # Capture the task run call because moto does not track 'networkConfiguration'
+        original_run_task = worker._create_task_run
+        mock_run_task = MagicMock(side_effect=original_run_task)
+        worker._create_task_run = mock_run_task
+
+        result = await run_then_stop_task(worker, configuration, flow_run)
+
+    assert result.status_code == 0
+    network_configuration = mock_run_task.call_args[0][1].get("networkConfiguration")
+
+    # Subnet ids are copied from the vpc
+    assert network_configuration == {
+        "awsvpcConfiguration": {
+            "subnets": subnet_ids,
+            "assignPublicIp": "DISABLED",
+            "securityGroups": [security_group.id],
+        }
+    }
+
+
 @pytest.mark.usefixtures("ecs_mocks")
 async def test_network_config_from_custom_settings_invalid_subnet(
     aws_credentials: AwsCredentials, flow_run: FlowRun
@@ -978,6 +1079,48 @@ async def test_network_config_from_custom_settings_invalid_subnet(
             await run_then_stop_task(worker, configuration, flow_run)
 
 
+@pytest.mark.usefixtures("ecs_mocks")
+async def test_network_config_from_custom_settings_invalid_subnet_multiple_vpc_subnets(
+    aws_credentials: AwsCredentials, flow_run: FlowRun
+):
+    session = aws_credentials.get_boto3_session()
+    ec2_resource = session.resource("ec2")
+    vpc = ec2_resource.create_vpc(CidrBlock="10.0.0.0/16")
+    security_group = ec2_resource.create_security_group(
+        GroupName="ECSWorkerTestSG", Description="ECS Worker test SG", VpcId=vpc.id
+    )
+    subnet = ec2_resource.create_subnet(CidrBlock="10.0.2.0/24", VpcId=vpc.id)
+    invalid_subnet_id = "subnet-3bf19de7"
+
+    configuration = await construct_configuration(
+        aws_credentials=aws_credentials,
+        vpc_id=vpc.id,
+        override_network_configuration=True,
+        network_configuration={
+            "subnets": [invalid_subnet_id, subnet.id],
+            "assignPublicIp": "DISABLED",
+            "securityGroups": [security_group.id],
+        },
+    )
+
+    session = aws_credentials.get_boto3_session()
+
+    with pytest.raises(
+        ValueError,
+        match=(
+            rf"Subnets \['{invalid_subnet_id}', '{subnet.id}'\] not found within VPC"
+            f" with ID {vpc.id}.Please check that VPC is associated with supplied"
+            " subnets."
+        ),
+    ):
+        async with ECSWorker(work_pool_name="test") as worker:
+            original_run_task = worker._create_task_run
+            mock_run_task = MagicMock(side_effect=original_run_task)
+            worker._create_task_run = mock_run_task
+
+            await run_then_stop_task(worker, configuration, flow_run)
+
+
 @pytest.mark.usefixtures("ecs_mocks")
 async def test_network_config_configure_network_requires_vpc_id(
     aws_credentials: AwsCredentials, flow_run: FlowRun