diff --git a/internal/translator/gemini-cli/openai/chat-completions/cli_openai_request.go b/internal/translator/gemini-cli/openai/chat-completions/cli_openai_request.go
index 6ed48486..c69ecf30 100644
--- a/internal/translator/gemini-cli/openai/chat-completions/cli_openai_request.go
+++ b/internal/translator/gemini-cli/openai/chat-completions/cli_openai_request.go
@@ -79,6 +79,12 @@ func ConvertOpenAIRequestToGeminiCLI(modelName string, inputRawJSON []byte, _ bo
 		out, _ = sjson.SetBytes(out, "request.generationConfig.topK", tkr.Num)
 	}
 
+	// Image config passthrough (e.g., aspectRatio)
+	// If the input carries generationConfig.imageConfig, preserve it in the Gemini CLI request.
+	if imgCfg := gjson.GetBytes(rawJSON, "generationConfig.imageConfig"); imgCfg.Exists() && imgCfg.IsObject() {
+		out, _ = sjson.SetRawBytes(out, "request.generationConfig.imageConfig", []byte(imgCfg.Raw))
+	}
+
 	// messages -> systemInstruction + contents
 	messages := gjson.GetBytes(rawJSON, "messages")
 	if messages.IsArray() {
diff --git a/internal/translator/gemini/openai/chat-completions/gemini_openai_request.go b/internal/translator/gemini/openai/chat-completions/gemini_openai_request.go
index 447bba31..4c5111e7 100644
--- a/internal/translator/gemini/openai/chat-completions/gemini_openai_request.go
+++ b/internal/translator/gemini/openai/chat-completions/gemini_openai_request.go
@@ -79,6 +79,12 @@ func ConvertOpenAIRequestToGemini(modelName string, inputRawJSON []byte, _ bool)
 		out, _ = sjson.SetBytes(out, "generationConfig.topK", tkr.Num)
 	}
 
+	// Image config passthrough (e.g., aspectRatio)
+	// If the input carries generationConfig.imageConfig, preserve it in the Gemini request.
+	if imgCfg := gjson.GetBytes(rawJSON, "generationConfig.imageConfig"); imgCfg.Exists() && imgCfg.IsObject() {
+		out, _ = sjson.SetRawBytes(out, "generationConfig.imageConfig", []byte(imgCfg.Raw))
+	}
+
 	// messages -> systemInstruction + contents
 	messages := gjson.GetBytes(rawJSON, "messages")
 	if messages.IsArray() {
diff --git a/internal/translator/gemini/openai/responses/gemini_openai-responses_request.go b/internal/translator/gemini/openai/responses/gemini_openai-responses_request.go
index af7923ab..9ed23bc5 100644
--- a/internal/translator/gemini/openai/responses/gemini_openai-responses_request.go
+++ b/internal/translator/gemini/openai/responses/gemini_openai-responses_request.go
@@ -262,5 +262,11 @@ func ConvertOpenAIResponsesRequestToGemini(modelName string, inputRawJSON []byte
 		}
 	}
 
+	// Image config passthrough (e.g., aspectRatio)
+	// If the input carries generationConfig.imageConfig, preserve it in the Gemini request.
+	if imgCfg := root.Get("generationConfig.imageConfig"); imgCfg.Exists() && imgCfg.IsObject() {
+		out, _ = sjson.SetRaw(out, "generationConfig.imageConfig", imgCfg.Raw)
+	}
+
 	return []byte(out)
 }