diff --git a/Source/Core/Core/IOS/Network/KD/NWC24Config.cpp b/Source/Core/Core/IOS/Network/KD/NWC24Config.cpp
index 940a5360dd..8900f00239 100644
--- a/Source/Core/Core/IOS/Network/KD/NWC24Config.cpp
+++ b/Source/Core/Core/IOS/Network/KD/NWC24Config.cpp
@@ -228,4 +228,22 @@ std::string NWC24Config::GetCheckURL() const
   const size_t size = strnlen(m_data.http_urls[1], MAX_URL_LENGTH);
   return {m_data.http_urls[1], size};
 }
+
+std::string NWC24Config::GetAccountURL() const
+{
+  const size_t size = strnlen(m_data.http_urls[0], MAX_URL_LENGTH);
+  return {m_data.http_urls[0], size};
+}
+
+void NWC24Config::SetMailCheckID(std::string_view mlchkid)
+{
+  std::strncpy(m_data.mlchkid, mlchkid.data(), std::size(m_data.mlchkid));
+  m_data.mlchkid[MAX_MLCHKID_LENGTH - 1] = '\0';
+}
+
+void NWC24Config::SetPassword(std::string_view password)
+{
+  std::strncpy(m_data.paswd, password.data(), std::size(m_data.paswd));
+  m_data.paswd[MAX_PASSWORD_LENGTH - 1] = '\0';
+}
 }  // namespace IOS::HLE::NWC24
diff --git a/Source/Core/Core/IOS/Network/KD/NWC24Config.h b/Source/Core/Core/IOS/Network/KD/NWC24Config.h
index 26d37009ff..3f1f7e8e90 100644
--- a/Source/Core/Core/IOS/Network/KD/NWC24Config.h
+++ b/Source/Core/Core/IOS/Network/KD/NWC24Config.h
@@ -29,7 +29,7 @@ enum ErrorCode : s32
   WC24_ERR_FILE_WRITE = -19,
   WC24_ERR_NETWORK = -31,
   WC24_ERR_SERVER = -32,
-  WC24_ERR_ID_NONEXISTANCE = -34,
+  WC24_ERR_ID_NOT_GENERATED = -34,
   WC24_ERR_ID_GENERATED = -35,
   WC24_ERR_ID_REGISTERED = -36,
   WC24_ERR_DISABLED = -39,
@@ -89,6 +89,10 @@ public:
   const char* Email() const;
   void SetEmail(const char* email);
 
+  std::string GetAccountURL() const;
+  void SetMailCheckID(std::string_view mlchkid);
+  void SetPassword(std::string_view password);
+
 private:
   enum
   {
diff --git a/Source/Core/Core/IOS/Network/KD/NetKDRequest.cpp b/Source/Core/Core/IOS/Network/KD/NetKDRequest.cpp
index 833bc5707f..c45dca0158 100644
--- a/Source/Core/Core/IOS/Network/KD/NetKDRequest.cpp
+++ b/Source/Core/Core/IOS/Network/KD/NetKDRequest.cpp
@@ -17,6 +17,7 @@
 #include "Common/Logging/Log.h"
 #include "Common/NandPaths.h"
 #include "Common/SettingsHandler.h"
+#include "Common/StringUtil.h"
 
 #include "Common/Random.h"
 #include "Common/ScopeGuard.h"
@@ -691,6 +692,103 @@ IPCReply NetKDRequestDevice::HandleNWC24DownloadNowEx(const IOCtlRequest& reques
   return IPCReply(IPC_SUCCESS);
 }
 
+IPCReply NetKDRequestDevice::HandleRequestRegisterUserId(const IOS::HLE::IOCtlRequest& request)
+{
+  auto& system = GetSystem();
+  auto& memory = system.GetMemory();
+
+  INFO_LOG_FMT(IOS_WC24, "NET_KD_REQ: IOCTL_NWC24_REQUEST_REGISTER_USER_ID");
+  // Always 0 for some reason, never modified anywhere else
+  memory.Write_U32(0, request.buffer_out + 4);
+
+  // First check if the message config file is in the correct state to handle this.
+  if (m_config.IsRegistered())
+  {
+    WriteReturnValue(NWC24::WC24_ERR_ID_REGISTERED, request.buffer_out);
+    LogError(ErrorType::Account, NWC24::WC24_ERR_ID_REGISTERED);
+    return IPCReply{IPC_SUCCESS};
+  }
+
+  if (!m_config.IsGenerated())
+  {
+    WriteReturnValue(NWC24::WC24_ERR_ID_NOT_GENERATED, request.buffer_out);
+    LogError(ErrorType::Account, NWC24::WC24_ERR_ID_NOT_GENERATED);
+    return IPCReply{IPC_SUCCESS};
+  }
+
+  // We require the user's serial number.
+  const std::string settings_file_path =
+      Common::GetTitleDataPath(Titles::SYSTEM_MENU) + "/" WII_SETTING;
+  const auto file = m_ios.GetFS()->OpenFile(PID_KD, PID_KD, settings_file_path, FS::Mode::Read);
+  if (!file)
+  {
+    WriteReturnValue(NWC24::WC24_ERR_FILE_OPEN, request.buffer_out);
+    LogError(ErrorType::Account, NWC24::WC24_ERR_FILE_OPEN);
+    return IPCReply{IPC_SUCCESS};
+  }
+
+  Common::SettingsHandler::Buffer data;
+  if (!file->Read(data.data(), data.size()))
+  {
+    WriteReturnValue(NWC24::WC24_ERR_FILE_READ, request.buffer_out);
+    LogError(ErrorType::Account, NWC24::WC24_ERR_FILE_READ);
+    return IPCReply{IPC_SUCCESS};
+  }
+
+  const Common::SettingsHandler gen{std::move(data)};
+  const std::string serno = gen.GetValue("SERNO");
+  const std::string form_data =
+      fmt::format("mlid=w{}&hdid={}&rgncd={}", m_config.Id(), m_ios.GetIOSC().GetDeviceId(), serno);
+  const Common::HttpRequest::Response response = m_http.Post(m_config.GetAccountURL(), form_data);
+
+  if (!response)
+  {
+    ERROR_LOG_FMT(IOS_WC24,
+                  "NET_KD_REQ: IOCTL_NWC24_REQUEST_REGISTER_USER_ID: Failed to request data at {}.",
+                  m_config.GetAccountURL());
+    WriteReturnValue(NWC24::WC24_ERR_SERVER, request.buffer_out);
+    LogError(ErrorType::Account, NWC24::WC24_ERR_SERVER);
+    return IPCReply{IPC_SUCCESS};
+  }
+
+  const std::string response_str = {response->begin(), response->end()};
+  const std::string code = GetValueFromCGIResponse(response_str, "cd");
+  if (code != "100")
+  {
+    ERROR_LOG_FMT(IOS_WC24,
+                  "NET_KD_REQ: IOCTL_NWC24_REQUEST_REGISTER_USER_ID: Mail server returned "
+                  "non-success code: {}",
+                  code);
+    WriteReturnValue(NWC24::WC24_ERR_SERVER, request.buffer_out);
+    LogError(ErrorType::Account, NWC24::WC24_ERR_SERVER);
+    return IPCReply{IPC_SUCCESS};
+  }
+
+  const std::string password = GetValueFromCGIResponse(response_str, "passwd");
+  const std::string mail_check_id = GetValueFromCGIResponse(response_str, "mlchkid");
+  if (mail_check_id.size() != 32)
+  {
+    ERROR_LOG_FMT(IOS_WC24,
+                  "NET_KD_REQ: IOCTL_NWC24_REQUEST_REGISTER_USER_ID: Mail server returned invalid "
+                  "mlchkid: {}",
+                  mail_check_id);
+    WriteReturnValue(NWC24::WC24_ERR_SERVER, request.buffer_out);
+    LogError(ErrorType::Account, NWC24::WC24_ERR_SERVER);
+    return IPCReply{IPC_SUCCESS};
+  }
+
+  // Now write to the config.
+  m_config.SetCreationStage(NWC24::NWC24CreationStage::Registered);
+  m_config.SetPassword(password);
+  m_config.SetMailCheckID(mail_check_id);
+  m_config.WriteConfig();
+  m_config.WriteCBK();
+
+  WriteReturnValue(NWC24::WC24_OK, request.buffer_out);
+
+  return IPCReply{IPC_SUCCESS};
+}
+
 std::optional<IPCReply> NetKDRequestDevice::IOCtl(const IOCtlRequest& request)
 {
   enum : u32
@@ -760,10 +858,7 @@ std::optional<IPCReply> NetKDRequestDevice::IOCtl(const IOCtlRequest& request)
     break;
 
   case IOCTL_NWC24_REQUEST_REGISTER_USER_ID:
-    INFO_LOG_FMT(IOS_WC24, "NET_KD_REQ: IOCTL_NWC24_REQUEST_REGISTER_USER_ID");
-    WriteReturnValue(0, request.buffer_out);
-    memory.Write_U32(0, request.buffer_out + 4);
-    break;
+    return LaunchAsyncTask(&NetKDRequestDevice::HandleRequestRegisterUserId, request);
 
   case IOCTL_NWC24_REQUEST_GENERATED_USER_ID:  // (Input: none, Output: 32 bytes)
     INFO_LOG_FMT(IOS_WC24, "NET_KD_REQ: IOCTL_NWC24_REQUEST_GENERATED_USER_ID");
diff --git a/Source/Core/Core/IOS/Network/KD/NetKDRequest.h b/Source/Core/Core/IOS/Network/KD/NetKDRequest.h
index 99130cec6b..4db2c26eff 100644
--- a/Source/Core/Core/IOS/Network/KD/NetKDRequest.h
+++ b/Source/Core/Core/IOS/Network/KD/NetKDRequest.h
@@ -81,7 +81,7 @@ private:
   };
 
   NWC24::ErrorCode KDCheckMail(u32* mail_flag, u32* interval);
-
+  IPCReply HandleRequestRegisterUserId(const IOCtlRequest& request);
   void LogError(ErrorType error_type, s32 error_code);
   void SchedulerTimer();
   void SchedulerWorker(SchedulerEvent event);