diff --git a/README.md b/README.md
index 7d92bac3..f4d8ed82 100644
--- a/README.md
+++ b/README.md
@@ -229,6 +229,7 @@ console.log(await claudeResponse.json());
 - gemini-2.5-flash
 - gemini-2.5-flash-lite
 - gpt-5
+- gpt-5-codex
 - claude-opus-4-1-20250805
 - claude-opus-4-20250514
 - claude-sonnet-4-20250514
@@ -262,6 +263,7 @@ The server uses a YAML configuration file (`config.yaml`) located in the project
 | `debug`                                 | boolean  | false              | Enable debug mode for verbose logging.                                                                                                                                                    |
 | `api-keys`                              | string[] | []                 | List of API keys that can be used to authenticate requests.                                                                                                                               |
 | `generative-language-api-key`           | string[] | []                 | List of Generative Language API keys.                                                                                                                                                     |
+| `force-gpt-5-codex`                     | bool     | false              | Force the conversion of GPT-5 calls to GPT-5 Codex.                                                                                                                                       |
 | `codex-api-key`                         | object   | {}                 | List of Codex API keys.                                                                                                                                                                   |
 | `codex-api-key.api-key`                 | string   | ""                 | Codex API key.                                                                                                                                                                            |
 | `codex-api-key.base-url`                | string   | ""                 | Custom Codex API endpoint, if you use a third-party API endpoint.                                                                                                                         |
@@ -322,6 +324,9 @@ generative-language-api-key:
   - "AIzaSy...03"
   - "AIzaSy...04"
 
+# Force the conversion of GPT-5 calls to GPT-5 Codex.
+force-gpt-5-codex: true
+
 # Codex API keys
 codex-api-key:
   - api-key: "sk-atSM..."
@@ -423,7 +428,7 @@ export ANTHROPIC_MODEL=gemini-2.5-pro
 export ANTHROPIC_SMALL_FAST_MODEL=gemini-2.5-flash
 ```
 
-Using OpenAI models:
+Using OpenAI GPT 5 models:
 ```bash
 export ANTHROPIC_BASE_URL=http://127.0.0.1:8317
 export ANTHROPIC_AUTH_TOKEN=sk-dummy
@@ -431,6 +436,14 @@ export ANTHROPIC_MODEL=gpt-5
 export ANTHROPIC_SMALL_FAST_MODEL=gpt-5-minimal
 ```
 
+Using OpenAI GPT 5 Codex models:
+```bash
+export ANTHROPIC_BASE_URL=http://127.0.0.1:8317
+export ANTHROPIC_AUTH_TOKEN=sk-dummy
+export ANTHROPIC_MODEL=gpt-5-codex
+export ANTHROPIC_SMALL_FAST_MODEL=gpt-5-codex-low
+```
+
 Using Claude models:
 ```bash
 export ANTHROPIC_BASE_URL=http://127.0.0.1:8317
@@ -454,7 +467,7 @@ Start CLI Proxy API server, and then edit the `~/.codex/config.toml` and `~/.cod
 config.toml:
 ```toml
 model_provider = "cliproxyapi"
-model = "gpt-5" # You can use any of the models that we support.
+model = "gpt-5-codex" # Or gpt-5, you can also use any of the models that we support.
 model_reasoning_effort = "high"
 
 [model_providers.cliproxyapi]
diff --git a/README_CN.md b/README_CN.md
index 1b89a51e..bd0395a9 100644
--- a/README_CN.md
+++ b/README_CN.md
@@ -241,6 +241,7 @@ console.log(await claudeResponse.json());
 - gemini-2.5-flash
 - gemini-2.5-flash-lite
 - gpt-5
+- gpt-5-codex
 - claude-opus-4-1-20250805
 - claude-opus-4-20250514
 - claude-sonnet-4-20250514
@@ -274,6 +275,7 @@ console.log(await claudeResponse.json());
 | `debug`                                 | boolean  | false              | 启用调试模式以获取详细日志。                                                      |
 | `api-keys`                              | string[] | []                 | 可用于验证请求的API密钥列表。                                                    |
 | `generative-language-api-key`           | string[] | []                 | 生成式语言API密钥列表。                                                       |
+| `force-gpt-5-codex`                     | bool     | false              | 强制将 GPT-5 调用转换成 GPT-5 Codex.                                        |
 | `codex-api-key`                         | object   | {}                 | Codex API密钥列表。                                                      |
 | `codex-api-key.api-key`                 | string   | ""                 | Codex API密钥。                                                        |
 | `codex-api-key.base-url`                | string   | ""                 | 自定义的Codex API端点                                                     |
@@ -334,6 +336,9 @@ generative-language-api-key:
   - "AIzaSy...03"
   - "AIzaSy...04"
 
+# 强制将 GPT-5 调用转换成 GPT-5 Codex.
+force-gpt-5-codex: true
+
 # Codex API 密钥
 codex-api-key:
   - api-key: "sk-atSM..."
@@ -430,7 +435,7 @@ export ANTHROPIC_MODEL=gemini-2.5-pro
 export ANTHROPIC_SMALL_FAST_MODEL=gemini-2.5-flash
 ```
 
-使用 OpenAI 模型：
+使用 OpenAI GPT 5 模型：
 ```bash
 export ANTHROPIC_BASE_URL=http://127.0.0.1:8317
 export ANTHROPIC_AUTH_TOKEN=sk-dummy
@@ -438,6 +443,15 @@ export ANTHROPIC_MODEL=gpt-5
 export ANTHROPIC_SMALL_FAST_MODEL=gpt-5-minimal
 ```
 
+使用 OpenAI GPT 5 Codex 模型:
+```bash
+export ANTHROPIC_BASE_URL=http://127.0.0.1:8317
+export ANTHROPIC_AUTH_TOKEN=sk-dummy
+export ANTHROPIC_MODEL=gpt-5-codex
+export ANTHROPIC_SMALL_FAST_MODEL=gpt-5-codex-low
+```
+
+
 使用 Claude 模型：
 ```bash
 export ANTHROPIC_BASE_URL=http://127.0.0.1:8317
@@ -461,7 +475,7 @@ export ANTHROPIC_SMALL_FAST_MODEL=qwen3-coder-flash
 config.toml:
 ```toml
 model_provider = "cliproxyapi"
-model = "gpt-5" # 你可以使用任何我们支持的模型
+model = "gpt-5-codex" # 或者是gpt-5，你也可以使用任何我们支持的模型
 model_reasoning_effort = "high"
 
 [model_providers.cliproxyapi]
diff --git a/config.example.yaml b/config.example.yaml
index 4281e24e..855b9ad6 100644
--- a/config.example.yaml
+++ b/config.example.yaml
@@ -41,6 +41,9 @@ generative-language-api-key:
   - "AIzaSy...03"
   - "AIzaSy...04"
 
+# forces the use of GPT-5 Codex model.
+gpt-5-codex: true
+
 # Codex API keys
 codex-api-key:
   - api-key: "sk-atSM..."
diff --git a/internal/api/handlers/management/config_basic.go b/internal/api/handlers/management/config_basic.go
index 57af692c..346e24ff 100644
--- a/internal/api/handlers/management/config_basic.go
+++ b/internal/api/handlers/management/config_basic.go
@@ -12,6 +12,14 @@ func (h *Handler) GetConfig(c *gin.Context) {
 func (h *Handler) GetDebug(c *gin.Context) { c.JSON(200, gin.H{"debug": h.cfg.Debug}) }
 func (h *Handler) PutDebug(c *gin.Context) { h.updateBoolField(c, func(v bool) { h.cfg.Debug = v }) }
 
+// ForceGPT5Codex
+func (h *Handler) GetForceGPT5Codex(c *gin.Context) {
+	c.JSON(200, gin.H{"gpt-5-codex": h.cfg.ForceGPT5Codex})
+}
+func (h *Handler) PutForceGPT5Codex(c *gin.Context) {
+	h.updateBoolField(c, func(v bool) { h.cfg.ForceGPT5Codex = v })
+}
+
 // Request log
 func (h *Handler) GetRequestLog(c *gin.Context) { c.JSON(200, gin.H{"request-log": h.cfg.RequestLog}) }
 func (h *Handler) PutRequestLog(c *gin.Context) {
diff --git a/internal/api/server.go b/internal/api/server.go
index 5842801b..e8e56fe2 100644
--- a/internal/api/server.go
+++ b/internal/api/server.go
@@ -200,6 +200,10 @@ func (s *Server) setupRoutes() {
 			mgmt.PUT("/debug", s.mgmt.PutDebug)
 			mgmt.PATCH("/debug", s.mgmt.PutDebug)
 
+			mgmt.GET("/force-gpt-5-codex", s.mgmt.GetForceGPT5Codex)
+			mgmt.PUT("/force-gpt-5-codex", s.mgmt.PutForceGPT5Codex)
+			mgmt.PATCH("/force-gpt-5-codex", s.mgmt.PutForceGPT5Codex)
+
 			mgmt.GET("/proxy-url", s.mgmt.GetProxyURL)
 			mgmt.PUT("/proxy-url", s.mgmt.PutProxyURL)
 			mgmt.PATCH("/proxy-url", s.mgmt.PutProxyURL)
diff --git a/internal/client/codex_client.go b/internal/client/codex_client.go
index 37fb99de..87bb8105 100644
--- a/internal/client/codex_client.go
+++ b/internal/client/codex_client.go
@@ -136,6 +136,10 @@ func (c *CodexClient) CanProvideModel(modelName string) bool {
 		"gpt-5-low",
 		"gpt-5-medium",
 		"gpt-5-high",
+		"gpt-5-codex",
+		"gpt-5-codex-low",
+		"gpt-5-codex-medium",
+		"gpt-5-codex-high",
 		"codex-mini-latest",
 	}
 	return util.InArray(models, modelName)
@@ -415,6 +419,25 @@ func (c *CodexClient) APIRequest(ctx context.Context, modelName, endpoint string
 		case "gpt-5-high":
 			jsonBody, _ = sjson.SetBytes(jsonBody, "reasoning.effort", "high")
 		}
+	} else if util.InArray([]string{"gpt-5-codex", "gpt-5-codex-low", "gpt-5-codex-medium", "gpt-5-codex-high"}, modelName) {
+		jsonBody, _ = sjson.SetBytes(jsonBody, "model", "gpt-5-codex")
+		switch modelName {
+		case "gpt-5-codex":
+			jsonBody, _ = sjson.SetBytes(jsonBody, "reasoning.effort", "medium")
+		case "gpt-5-codex-low":
+			jsonBody, _ = sjson.SetBytes(jsonBody, "reasoning.effort", "low")
+		case "gpt-5-codex-medium":
+			jsonBody, _ = sjson.SetBytes(jsonBody, "reasoning.effort", "medium")
+		case "gpt-5-codex-high":
+			jsonBody, _ = sjson.SetBytes(jsonBody, "reasoning.effort", "high")
+		}
+	} else if c.cfg.ForceGPT5Codex {
+		if gjson.GetBytes(jsonBody, "model").String() == "gpt-5" {
+			if gjson.GetBytes(jsonBody, "reasoning.effort").String() == "minimal" {
+				jsonBody, _ = sjson.SetBytes(jsonBody, "reasoning.effort", "low")
+			}
+			jsonBody, _ = sjson.SetBytes(jsonBody, "model", "gpt-5-codex")
+		}
 	}
 
 	url := fmt.Sprintf("%s%s", chatGPTEndpoint, endpoint)
diff --git a/internal/config/config.go b/internal/config/config.go
index a3a87a56..ce4fb257 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -44,6 +44,9 @@ type Config struct {
 	// ClaudeKey defines a list of Claude API key configurations as specified in the YAML configuration file.
 	ClaudeKey []ClaudeKey `yaml:"claude-api-key" json:"claude-api-key"`
 
+	// ForceGPT5Codex forces the use of GPT-5 Codex model.
+	ForceGPT5Codex bool `yaml:"force-gpt-5-codex" json:"force-gpt-5-codex"`
+
 	// Codex defines a list of Codex API key configurations as specified in the YAML configuration file.
 	CodexKey []CodexKey `yaml:"codex-api-key" json:"codex-api-key"`
 
diff --git a/internal/registry/model_definitions.go b/internal/registry/model_definitions.go
index 83456f30..aab7e973 100644
--- a/internal/registry/model_definitions.go
+++ b/internal/registry/model_definitions.go
@@ -215,6 +215,58 @@ func GetOpenAIModels() []*ModelInfo {
 			MaxCompletionTokens: 128000,
 			SupportedParameters: []string{"tools"},
 		},
+		{
+			ID:                  "gpt-5-codex",
+			Object:              "model",
+			Created:             time.Now().Unix(),
+			OwnedBy:             "openai",
+			Type:                "openai",
+			Version:             "gpt-5-2025-09-15",
+			DisplayName:         "GPT 5 Codex",
+			Description:         "Stable version of GPT 5 Codex, The best model for coding and agentic tasks across domains.",
+			ContextLength:       400000,
+			MaxCompletionTokens: 128000,
+			SupportedParameters: []string{"tools"},
+		},
+		{
+			ID:                  "gpt-5-codex-low",
+			Object:              "model",
+			Created:             time.Now().Unix(),
+			OwnedBy:             "openai",
+			Type:                "openai",
+			Version:             "gpt-5-2025-09-15",
+			DisplayName:         "GPT 5 Codex Low",
+			Description:         "Stable version of GPT 5 Codex, The best model for coding and agentic tasks across domains.",
+			ContextLength:       400000,
+			MaxCompletionTokens: 128000,
+			SupportedParameters: []string{"tools"},
+		},
+		{
+			ID:                  "gpt-5-codex-medium",
+			Object:              "model",
+			Created:             time.Now().Unix(),
+			OwnedBy:             "openai",
+			Type:                "openai",
+			Version:             "gpt-5-2025-09-15",
+			DisplayName:         "GPT 5 Codex Medium",
+			Description:         "Stable version of GPT 5 Codex, The best model for coding and agentic tasks across domains.",
+			ContextLength:       400000,
+			MaxCompletionTokens: 128000,
+			SupportedParameters: []string{"tools"},
+		},
+		{
+			ID:                  "gpt-5-codex-high",
+			Object:              "model",
+			Created:             time.Now().Unix(),
+			OwnedBy:             "openai",
+			Type:                "openai",
+			Version:             "gpt-5-2025-09-15",
+			DisplayName:         "GPT 5 Codex High",
+			Description:         "Stable version of GPT 5 Codex, The best model for coding and agentic tasks across domains.",
+			ContextLength:       400000,
+			MaxCompletionTokens: 128000,
+			SupportedParameters: []string{"tools"},
+		},
 		{
 			ID:                  "codex-mini-latest",
 			Object:              "model",
diff --git a/internal/watcher/watcher.go b/internal/watcher/watcher.go
index 0214b086..1057763a 100644
--- a/internal/watcher/watcher.go
+++ b/internal/watcher/watcher.go
@@ -240,6 +240,9 @@ func (w *Watcher) reloadConfig() bool {
 		if oldConfig.RemoteManagement.AllowRemote != newConfig.RemoteManagement.AllowRemote {
 			log.Debugf("  remote-management.allow-remote: %t -> %t", oldConfig.RemoteManagement.AllowRemote, newConfig.RemoteManagement.AllowRemote)
 		}
+		if oldConfig.ForceGPT5Codex != newConfig.ForceGPT5Codex {
+			log.Debugf("  gpt-5-codex: %t -> %t", oldConfig.ForceGPT5Codex, newConfig.ForceGPT5Codex)
+		}
 	}
 
 	log.Infof("config successfully reloaded, triggering client reload")