diff --git a/localization/strings/en-US/Resources.resw b/localization/strings/en-US/Resources.resw
index de258d29d..602696521 100644
--- a/localization/strings/en-US/Resources.resw
+++ b/localization/strings/en-US/Resources.resw
@@ -1982,6 +1982,9 @@ Usage:
     <value>Container '{}' not found.</value>
     <comment>{FixedPlaceholder="{}"}Command line arguments, file names and string inserts should not be translated</comment>
   </data>
+  <data name="MessageWslcContainerNetworkNameRequired" xml:space="preserve">
+    <value>Container network name is required for custom network type.</value>
+  </data>
   <data name="WSLCCLI_UnrecognizedCommandError" xml:space="preserve">
     <value>Unrecognized command: '{}'</value>
     <comment>{FixedPlaceholder="{}"}Command line arguments, file names and string inserts should not be translated</comment>
diff --git a/src/windows/common/WSLCContainerLauncher.cpp b/src/windows/common/WSLCContainerLauncher.cpp
index 3d75c7d73..68b0e768b 100644
--- a/src/windows/common/WSLCContainerLauncher.cpp
+++ b/src/windows/common/WSLCContainerLauncher.cpp
@@ -139,6 +139,11 @@ void WSLCContainerLauncher::SetContainerFlags(WSLCContainerFlags Flags)
     m_containerFlags = Flags;
 }
 
+void WSLCContainerLauncher::SetContainerNetworkName(std::string&& Name)
+{
+    m_containerNetworkName = std::move(Name);
+}
+
 void WSLCContainerLauncher::SetHostname(std::string&& Hostname)
 {
     m_hostname = std::move(Hostname);
@@ -250,6 +255,7 @@ std::pair<HRESULT, std::optional<RunningWSLCContainer>> WSLCContainerLauncher::C
     auto [processOptions, commandLinePtrs, environmentPtrs] = CreateProcessOptions();
     options.InitProcessOptions = processOptions;
     options.ContainerNetwork.ContainerNetworkType = m_containerNetworkType;
+    options.ContainerNetwork.ContainerNetworkName = m_containerNetworkName.empty() ? nullptr : m_containerNetworkName.c_str();
     options.Ports = m_ports.data();
     options.PortsCount = static_cast<ULONG>(m_ports.size());
     options.StopSignal = m_stopSignal;
diff --git a/src/windows/common/WSLCContainerLauncher.h b/src/windows/common/WSLCContainerLauncher.h
index 4643bc875..aed6badfc 100644
--- a/src/windows/common/WSLCContainerLauncher.h
+++ b/src/windows/common/WSLCContainerLauncher.h
@@ -73,6 +73,7 @@ class WSLCContainerLauncher : private WSLCProcessLauncher
     void SetEntrypoint(std::vector<std::string>&& entrypoint);
     void SetDefaultStopSignal(WSLCSignal Signal);
     void SetContainerFlags(WSLCContainerFlags Flags);
+    void SetContainerNetworkName(std::string&& Name);
     void SetHostname(std::string&& Hostname);
     void SetDomainname(std::string&& Domainame);
     void SetDnsServers(std::vector<std::string>&& DnsServers);
@@ -93,6 +94,7 @@ class WSLCContainerLauncher : private WSLCProcessLauncher
     std::deque<std::string> m_volumeNames;
     std::deque<std::string> m_containerPaths;
     WSLCContainerNetworkType m_containerNetworkType;
+    std::string m_containerNetworkName;
     std::vector<std::string> m_entrypoint;
     WSLCSignal m_stopSignal = WSLCSignalNone;
     WSLCContainerFlags m_containerFlags = WSLCContainerFlagsNone;
diff --git a/src/windows/service/inc/wslc.idl b/src/windows/service/inc/wslc.idl
index 70d61d5cf..928397251 100644
--- a/src/windows/service/inc/wslc.idl
+++ b/src/windows/service/inc/wslc.idl
@@ -231,7 +231,7 @@ typedef enum _WSLCContainerNetworkType
     WSLCContainerNetworkTypeNone = 0,
     WSLCContainerNetworkTypeHost = 1,
     WSLCContainerNetworkTypeBridged = 2,
-    // WSLCContainerNetworkTypeCustom = 3 // TODO: Implement when implementing custom networks
+    WSLCContainerNetworkTypeCustom = 3
 } WSLCContainerNetworkType;
 
 typedef struct _WSLCContainerNetwork
diff --git a/src/windows/wslcsession/WSLCContainer.cpp b/src/windows/wslcsession/WSLCContainer.cpp
index 65a0306db..7ae44d7a3 100644
--- a/src/windows/wslcsession/WSLCContainer.cpp
+++ b/src/windows/wslcsession/WSLCContainer.cpp
@@ -146,7 +146,7 @@ uint16_t AllocateEphemeralPort(int family, const char* address)
 
 // Builds port mapping list from container options and returns the network mode string.
 std::pair<std::vector<ContainerPortMapping>, std::string> ProcessPortMappings(
-    std::vector<_WSLCPortMapping>& requestedPorts, WSLCContainerNetworkType networkType, WSLCVirtualMachine& virtualMachine)
+    std::vector<_WSLCPortMapping>& requestedPorts, WSLCContainerNetworkType networkType, WSLCVirtualMachine& virtualMachine, WSLCSession& session, LPCSTR containerNetworkName)
 {
     // Determine network mode string.
     std::string networkMode;
@@ -162,6 +162,16 @@ std::pair<std::vector<ContainerPortMapping>, std::string> ProcessPortMappings(
     {
         networkMode = "none";
     }
+    else if (networkType == WSLCContainerNetworkTypeCustom)
+    {
+        THROW_HR_WITH_USER_ERROR_IF(
+            E_INVALIDARG, Localization::MessageWslcContainerNetworkNameRequired(), !containerNetworkName || strlen(containerNetworkName) == 0);
+
+        THROW_HR_WITH_USER_ERROR_IF(
+            WSLC_E_NETWORK_NOT_FOUND, Localization::MessageWslcNetworkNotFound(containerNetworkName), !session.HasNetwork(containerNetworkName));
+
+        networkMode = containerNetworkName;
+    }
     else
     {
         THROW_HR_MSG(E_INVALIDARG, "Invalid networking mode: %i", networkType);
@@ -185,8 +195,8 @@ std::pair<std::vector<ContainerPortMapping>, std::string> ProcessPortMappings(
 
         auto& entry = ports.emplace_back(VMPortMapping::FromWSLCPortMapping(e), e.ContainerPort);
 
-        // Only allocate port for bridged network. Host mode ports are allocated when the container starts.
-        if (networkType == WSLCContainerNetworkTypeBridged)
+        // Allocate VM ports for bridged and custom networks. Host mode ports are allocated when the container starts.
+        if (networkType == WSLCContainerNetworkTypeBridged || networkType == WSLCContainerNetworkTypeCustom)
         {
             entry.VmMapping.AssignVmPort(virtualMachine.AllocatePort(e.Family, e.Protocol));
         }
@@ -268,7 +278,11 @@ WSLCContainerNetworkType DockerNetworkModeToWSLCNetworkType(const std::string& m
         return WSLCContainerNetworkTypeNone;
     }
 
-    THROW_HR_MSG(E_INVALIDARG, "Invalid networking mode: %hs", mode.c_str());
+    // Reject Docker special syntaxes (container:<id>, service:<name>, etc.);
+    // any plain name is treated as a user-defined custom network.
+    THROW_HR_IF_MSG(E_INVALIDARG, mode.empty() || mode.find(':') != std::string::npos, "Unsupported Docker network mode: %hs", mode.c_str());
+
+    return WSLCContainerNetworkTypeCustom;
 }
 
 std::uint64_t ParseDockerTimestamp(const std::string& timestamp)
@@ -1330,7 +1344,12 @@ std::unique_ptr<WSLCContainerImpl> WSLCContainerImpl::Create(
     }
 
     // Process port mappings from container options.
-    auto [mappedPorts, networkMode] = ProcessPortMappings(ports, containerOptions.ContainerNetwork.ContainerNetworkType, virtualMachine);
+    auto [mappedPorts, networkMode] = ProcessPortMappings(
+        ports,
+        containerOptions.ContainerNetwork.ContainerNetworkType,
+        virtualMachine,
+        wslcSession,
+        containerOptions.ContainerNetwork.ContainerNetworkName);
 
     request.HostConfig.NetworkMode = networkMode;
 
@@ -1438,7 +1457,7 @@ std::unique_ptr<WSLCContainerImpl> WSLCContainerImpl::Open(
     {
         auto& inserted = ports.emplace_back(ContainerPortMapping{VMPortMapping::FromContainerMetaData(e), e.ContainerPort});
 
-        if (networkingMode == WSLCContainerNetworkTypeBridged)
+        if (networkingMode == WSLCContainerNetworkTypeBridged || networkingMode == WSLCContainerNetworkTypeCustom)
         {
             auto allocation = virtualMachine.TryAllocatePort(e.VmPort, e.Family, e.Protocol);
 
diff --git a/src/windows/wslcsession/WSLCSession.cpp b/src/windows/wslcsession/WSLCSession.cpp
index a755f846c..c9af7ebb2 100644
--- a/src/windows/wslcsession/WSLCSession.cpp
+++ b/src/windows/wslcsession/WSLCSession.cpp
@@ -2280,6 +2280,13 @@ try
 }
 CATCH_RETURN();
 
+bool WSLCSession::HasNetwork(const std::string& Name)
+{
+    ValidateName(Name.c_str(), WSLC_MAX_NETWORK_NAME_LENGTH);
+    std::lock_guard networksLock(m_networksLock);
+    return m_networks.contains(Name);
+}
+
 HRESULT WSLCSession::Terminate()
 try
 {
diff --git a/src/windows/wslcsession/WSLCSession.h b/src/windows/wslcsession/WSLCSession.h
index 935888b6a..d659713a1 100644
--- a/src/windows/wslcsession/WSLCSession.h
+++ b/src/windows/wslcsession/WSLCSession.h
@@ -137,6 +137,9 @@ class DECLSPEC_UUID("4877FEFC-4977-4929-A958-9F36AA1892A4") WSLCSession
     IFACEMETHOD(ListNetworks)(_Out_ WSLCNetworkInformation** Networks, _Out_ ULONG* Count) override;
     IFACEMETHOD(InspectNetwork)(_In_ LPCSTR Name, _Out_ LPSTR* Output) override;
 
+    // N.B. Caller must hold m_lock (shared) before calling this method.
+    __requires_lock_held(m_lock) bool HasNetwork(const std::string& Name);
+
     IFACEMETHOD(Terminate()) override;
 
     // ISupportErrorInfo
diff --git a/test/windows/WSLCTests.cpp b/test/windows/WSLCTests.cpp
index 7bde747f4..194369eef 100644
--- a/test/windows/WSLCTests.cpp
+++ b/test/windows/WSLCTests.cpp
@@ -5284,6 +5284,57 @@ class WSLCTests
         }
     }
 
+    WSLC_TEST_METHOD(ContainerCustomNetworkTest)
+    {
+        const std::string networkName = "custom-net-test";
+
+        LOG_IF_FAILED(m_defaultSession->DeleteNetwork(networkName.c_str()));
+
+        WSLCDriverOption opts[] = {{"Subnet", "172.30.0.0/16"}};
+
+        WSLCNetworkOptions networkOptions{};
+        networkOptions.Name = networkName.c_str();
+        networkOptions.Driver = "bridge";
+        networkOptions.DriverOpts = opts;
+        networkOptions.DriverOptsCount = ARRAYSIZE(opts);
+
+        VERIFY_SUCCEEDED(m_defaultSession->CreateNetwork(&networkOptions));
+
+        auto networkCleanup = wil::scope_exit([&]() { LOG_IF_FAILED(m_defaultSession->DeleteNetwork(networkName.c_str())); });
+
+        WSLCContainerLauncher launcher(
+            "debian:latest", "test-custom-network", {"sleep", "99999"}, {}, WSLCContainerNetworkType::WSLCContainerNetworkTypeCustom);
+        launcher.SetContainerNetworkName(std::string(networkName));
+
+        auto container = launcher.Launch(*m_defaultSession);
+        VERIFY_ARE_EQUAL(container.State(), WslcContainerStateRunning);
+        VERIFY_ARE_EQUAL(container.Inspect().HostConfig.NetworkMode, networkName);
+        VERIFY_SUCCEEDED(container.Get().Stop(WSLCSignalSIGTERM, 0));
+        VERIFY_ARE_EQUAL(container.State(), WslcContainerStateExited);
+        VERIFY_SUCCEEDED(container.Get().Delete(WSLCDeleteFlagsNone));
+    }
+
+    WSLC_TEST_METHOD(ContainerCustomNetworkNotFoundTest)
+    {
+        WSLCContainerLauncher launcher(
+            "debian:latest", "test-custom-network-notfound", {"sleep", "99999"}, {}, WSLCContainerNetworkType::WSLCContainerNetworkTypeCustom);
+        launcher.SetContainerNetworkName(std::string("nonexistent-net"));
+
+        auto retVal = launcher.LaunchNoThrow(*m_defaultSession);
+        VERIFY_ARE_EQUAL(WSLC_E_NETWORK_NOT_FOUND, retVal.first);
+        ValidateCOMErrorMessageContains(L"nonexistent-net");
+    }
+
+    WSLC_TEST_METHOD(ContainerCustomNetworkMissingNameTest)
+    {
+        WSLCContainerLauncher launcher(
+            "debian:latest", "test-custom-network-noname", {"sleep", "99999"}, {}, WSLCContainerNetworkType::WSLCContainerNetworkTypeCustom);
+
+        auto retVal = launcher.LaunchNoThrow(*m_defaultSession);
+        VERIFY_ARE_EQUAL(E_INVALIDARG, retVal.first);
+        ValidateCOMErrorMessageContains(L"Container network name is required");
+    }
+
     WSLC_TEST_METHOD(ContainerInspect)
     {
         // Helper to verify port mappings.