diff --git a/docs/telemetry.md b/docs/telemetry.md
index 9153e4d7..b308217f 100644
--- a/docs/telemetry.md
+++ b/docs/telemetry.md
@@ -154,6 +154,7 @@ Logs are timestamped records of specific events. The following events are logged
   - **Attributes**:
     - `prompt_length`
     - `prompt` (this attribute is excluded if `log_prompts_enabled` is configured to be `false`)
+    - `auth_type`
 
 - `gemini_cli.tool_call`: This event occurs for each function call.
   - **Attributes**:
@@ -177,6 +178,7 @@ Logs are timestamped records of specific events. The following events are logged
     - `error_type`
     - `status_code`
     - `duration_ms`
+    - `auth_type`
 
 - `gemini_cli.api_response`: This event occurs upon receiving a response from Gemini API.
   - **Attributes**:
@@ -190,6 +192,7 @@ Logs are timestamped records of specific events. The following events are logged
     - `thoughts_token_count`
     - `tool_token_count`
     - `response_text` (if applicable)
+    - `auth_type`
 
 ### Metrics
 
diff --git a/packages/cli/src/gemini.tsx b/packages/cli/src/gemini.tsx
index 8b58c46a..23990f6d 100644
--- a/packages/cli/src/gemini.tsx
+++ b/packages/cli/src/gemini.tsx
@@ -212,6 +212,7 @@ export async function main() {
     'event.timestamp': new Date().toISOString(),
     prompt: input,
     prompt_id,
+    auth_type: config.getContentGeneratorConfig().authType!,
     prompt_length: input.length,
   });
 
diff --git a/packages/cli/src/ui/hooks/useGeminiStream.test.tsx b/packages/cli/src/ui/hooks/useGeminiStream.test.tsx
index e0e21f55..7e45cab2 100644
--- a/packages/cli/src/ui/hooks/useGeminiStream.test.tsx
+++ b/packages/cli/src/ui/hooks/useGeminiStream.test.tsx
@@ -273,6 +273,13 @@ describe('useGeminiStream', () => {
       return clientInstance;
     });
 
+    const contentGeneratorConfig = {
+      model: 'test-model',
+      apiKey: 'test-key',
+      vertexai: false,
+      authType: AuthType.USE_GEMINI,
+    };
+
     mockConfig = {
       apiKey: 'test-api-key',
       model: 'gemini-pro',
@@ -307,6 +314,9 @@ describe('useGeminiStream', () => {
       },
       setQuotaErrorOccurred: vi.fn(),
       getQuotaErrorOccurred: vi.fn(() => false),
+      getContentGeneratorConfig: vi
+        .fn()
+        .mockReturnValue(contentGeneratorConfig),
     } as unknown as Config;
     mockOnDebugMessage = vi.fn();
     mockHandleSlashCommand = vi.fn().mockResolvedValue(false);
diff --git a/packages/cli/src/ui/hooks/useGeminiStream.ts b/packages/cli/src/ui/hooks/useGeminiStream.ts
index a9326528..05fb9835 100644
--- a/packages/cli/src/ui/hooks/useGeminiStream.ts
+++ b/packages/cli/src/ui/hooks/useGeminiStream.ts
@@ -223,7 +223,12 @@ export const useGeminiStream = (
         const trimmedQuery = query.trim();
         logUserPrompt(
           config,
-          new UserPromptEvent(trimmedQuery.length, prompt_id, trimmedQuery),
+          new UserPromptEvent(
+            trimmedQuery.length,
+            prompt_id,
+            config.getContentGeneratorConfig().authType!,
+            trimmedQuery,
+          ),
         );
         onDebugMessage(`User query: '${trimmedQuery}'`);
         await logger?.logMessage(MessageSenderType.USER, trimmedQuery);
diff --git a/packages/core/src/core/geminiChat.ts b/packages/core/src/core/geminiChat.ts
index f57425a3..ab4f602c 100644
--- a/packages/core/src/core/geminiChat.ts
+++ b/packages/core/src/core/geminiChat.ts
@@ -172,6 +172,7 @@ export class GeminiChat {
         this.config.getModel(),
         durationMs,
         prompt_id,
+        this.config.getContentGeneratorConfig().authType!,
         usageMetadata,
         responseText,
       ),
@@ -193,6 +194,7 @@ export class GeminiChat {
         errorMessage,
         durationMs,
         prompt_id,
+        this.config.getContentGeneratorConfig().authType!,
         errorType,
       ),
     );
diff --git a/packages/core/src/telemetry/clearcut-logger/clearcut-logger.ts b/packages/core/src/telemetry/clearcut-logger/clearcut-logger.ts
index 673233f3..b75d87ef 100644
--- a/packages/core/src/telemetry/clearcut-logger/clearcut-logger.ts
+++ b/packages/core/src/telemetry/clearcut-logger/clearcut-logger.ts
@@ -266,6 +266,10 @@ export class ClearcutLogger {
         gemini_cli_key: EventMetadataKey.GEMINI_CLI_PROMPT_ID,
         value: JSON.stringify(event.prompt_id),
       },
+      {
+        gemini_cli_key: EventMetadataKey.GEMINI_CLI_AUTH_TYPE,
+        value: JSON.stringify(event.auth_type),
+      },
     ];
 
     this.enqueueLogEvent(this.createLogEvent(new_prompt_event_name, data));
@@ -377,6 +381,10 @@ export class ClearcutLogger {
           EventMetadataKey.GEMINI_CLI_API_RESPONSE_TOOL_TOKEN_COUNT,
         value: JSON.stringify(event.tool_token_count),
       },
+      {
+        gemini_cli_key: EventMetadataKey.GEMINI_CLI_AUTH_TYPE,
+        value: JSON.stringify(event.auth_type),
+      },
     ];
 
     this.enqueueLogEvent(this.createLogEvent(api_response_event_name, data));
@@ -407,6 +415,10 @@ export class ClearcutLogger {
         gemini_cli_key: EventMetadataKey.GEMINI_CLI_API_ERROR_DURATION_MS,
         value: JSON.stringify(event.duration_ms),
       },
+      {
+        gemini_cli_key: EventMetadataKey.GEMINI_CLI_AUTH_TYPE,
+        value: JSON.stringify(event.auth_type),
+      },
     ];
 
     this.enqueueLogEvent(this.createLogEvent(api_error_event_name, data));
diff --git a/packages/core/src/telemetry/clearcut-logger/event-metadata-key.ts b/packages/core/src/telemetry/clearcut-logger/event-metadata-key.ts
index e8a74936..577c5c07 100644
--- a/packages/core/src/telemetry/clearcut-logger/event-metadata-key.ts
+++ b/packages/core/src/telemetry/clearcut-logger/event-metadata-key.ts
@@ -144,6 +144,9 @@ export enum EventMetadataKey {
 
   // Logs the Prompt Id
   GEMINI_CLI_PROMPT_ID = 35,
+
+  // Logs the Auth type for the prompt, api responses and errors.
+  GEMINI_CLI_AUTH_TYPE = 36,
 }
 
 export function getEventMetadataKey(
diff --git a/packages/core/src/telemetry/loggers.test.ts b/packages/core/src/telemetry/loggers.test.ts
index e7dd721f..13617946 100644
--- a/packages/core/src/telemetry/loggers.test.ts
+++ b/packages/core/src/telemetry/loggers.test.ts
@@ -127,7 +127,12 @@ describe('loggers', () => {
     } as unknown as Config;
 
     it('should log a user prompt', () => {
-      const event = new UserPromptEvent(11, 'prompt-id-8', 'test-prompt');
+      const event = new UserPromptEvent(
+        11,
+        'prompt-id-8',
+        AuthType.USE_VERTEX_AI,
+        'test-prompt',
+      );
 
       logUserPrompt(mockConfig, event);
 
@@ -151,7 +156,11 @@ describe('loggers', () => {
         getTargetDir: () => 'target-dir',
         getUsageStatisticsEnabled: () => true,
       } as unknown as Config;
-      const event = new UserPromptEvent(11, 'test-prompt');
+      const event = new UserPromptEvent(
+        11,
+        'test-prompt',
+        AuthType.CLOUD_SHELL,
+      );
 
       logUserPrompt(mockConfig, event);
 
@@ -202,6 +211,7 @@ describe('loggers', () => {
         'test-model',
         100,
         'prompt-id-1',
+        AuthType.LOGIN_WITH_GOOGLE,
         usageData,
         'test-response',
       );
@@ -226,6 +236,7 @@ describe('loggers', () => {
           total_token_count: 0,
           response_text: 'test-response',
           prompt_id: 'prompt-id-1',
+          auth_type: 'oauth-personal',
         },
       });
 
@@ -263,6 +274,7 @@ describe('loggers', () => {
         'test-model',
         100,
         'prompt-id-1',
+        AuthType.USE_GEMINI,
         usageData,
         'test-response',
         'test-error',
diff --git a/packages/core/src/telemetry/types.ts b/packages/core/src/telemetry/types.ts
index 46f86b89..9f6e1462 100644
--- a/packages/core/src/telemetry/types.ts
+++ b/packages/core/src/telemetry/types.ts
@@ -96,13 +96,20 @@ export class UserPromptEvent {
   'event.timestamp': string; // ISO 8601
   prompt_length: number;
   prompt_id: string;
+  auth_type: string;
   prompt?: string;
 
-  constructor(prompt_length: number, prompt_Id: string, prompt?: string) {
+  constructor(
+    prompt_length: number,
+    prompt_Id: string,
+    auth_type: string,
+    prompt?: string,
+  ) {
     this['event.name'] = 'user_prompt';
     this['event.timestamp'] = new Date().toISOString();
     this.prompt_length = prompt_length;
     this.prompt_id = prompt_Id;
+    this.auth_type = auth_type;
     this.prompt = prompt;
   }
 }
@@ -160,12 +167,14 @@ export class ApiErrorEvent {
   status_code?: number | string;
   duration_ms: number;
   prompt_id: string;
+  auth_type: string;
 
   constructor(
     model: string,
     error: string,
     duration_ms: number,
     prompt_id: string,
+    auth_type: string,
     error_type?: string,
     status_code?: number | string,
   ) {
@@ -177,6 +186,7 @@ export class ApiErrorEvent {
     this.status_code = status_code;
     this.duration_ms = duration_ms;
     this.prompt_id = prompt_id;
+    this.auth_type = auth_type;
   }
 }
 
@@ -195,11 +205,13 @@ export class ApiResponseEvent {
   total_token_count: number;
   response_text?: string;
   prompt_id: string;
+  auth_type: string;
 
   constructor(
     model: string,
     duration_ms: number,
     prompt_id: string,
+    auth_type: string,
     usage_data?: GenerateContentResponseUsageMetadata,
     response_text?: string,
     error?: string,
@@ -218,6 +230,7 @@ export class ApiResponseEvent {
     this.response_text = response_text;
     this.error = error;
     this.prompt_id = prompt_id;
+    this.auth_type = auth_type;
   }
 }