diff --git a/src/main/services/S3Storage.ts b/src/main/services/S3Storage.ts
index ae63e38745..73c7ddee2c 100644
--- a/src/main/services/S3Storage.ts
+++ b/src/main/services/S3Storage.ts
@@ -39,7 +39,7 @@ export default class S3Storage {
   private root: string
 
   constructor(config: S3Config) {
-    const { endpoint, region, accessKeyId, secretAccessKey, bucket, root } = config
+    const { endpoint, region, accessKeyId, secretAccessKey, bucket, root, bypassProxy = true } = config
 
     const usePathStyle = (() => {
       if (!endpoint) return false
@@ -59,22 +59,24 @@ export default class S3Storage {
       }
     })()
 
-    // Fix for S3 backup failure when using proxy
-    // Issue: When proxy is enabled, S3 uploads can fail with incomplete writes
-    // Error: "Io error: put_object write size < data.size(), w_size=15728640, data.size=16396159"
-    // Root cause: AWS SDK uses global fetch/undici dispatcher which routes through proxy,
-    //             causing data corruption or incomplete transfers for large files
-    // Solution: Configure S3Client with a direct dispatcher that bypasses the global proxy
-    const directDispatcher = new UndiciAgent({
-      connect: {
-        timeout: 60000 // 60 second connection timeout
-      }
-    })
+    // Conditionally bypass proxy for S3 requests based on user configuration
+    // When bypassProxy is true (default), S3 requests use a direct dispatcher to avoid
+    // proxy interference with large file uploads that can cause incomplete transfers
+    // Error example: "Io error: put_object write size < data.size(), w_size=15728640, data.size=16396159"
+    let requestHandler: FetchHttpHandler | undefined
 
-    const requestHandler = new FetchHttpHandler({
-      requestTimeout: 300000, // 5 minute request timeout for large files
-      dispatcher: directDispatcher
-    })
+    if (bypassProxy) {
+      const directDispatcher = new UndiciAgent({
+        connect: {
+          timeout: 60000 // 60 second connection timeout
+        }
+      })
+
+      requestHandler = new FetchHttpHandler({
+        requestTimeout: 300000, // 5 minute request timeout for large files
+        dispatcher: directDispatcher
+      })
+    }
 
     this.client = new S3Client({
       region,
@@ -84,7 +86,7 @@ export default class S3Storage {
         secretAccessKey: secretAccessKey
       },
       forcePathStyle: usePathStyle,
-      requestHandler
+      ...(requestHandler && { requestHandler })
     })
 
     this.bucket = bucket
diff --git a/src/renderer/src/i18n/locales/en-us.json b/src/renderer/src/i18n/locales/en-us.json
index 36ce60edb6..ac43774771 100644
--- a/src/renderer/src/i18n/locales/en-us.json
+++ b/src/renderer/src/i18n/locales/en-us.json
@@ -3419,6 +3419,10 @@
           "help": "When enabled, file data will be skipped during backup, only configuration information will be backed up, significantly reducing backup file size",
           "label": "Lightweight Backup"
         },
+        "bypassProxy": {
+          "help": "When enabled, S3 requests bypass the application proxy to prevent data corruption during large file uploads. Recommended to keep enabled unless your S3 endpoint requires proxy access.",
+          "label": "Bypass Proxy"
+        },
         "syncStatus": {
           "error": "Sync error: {{message}}",
           "label": "Sync Status",
diff --git a/src/renderer/src/i18n/locales/zh-cn.json b/src/renderer/src/i18n/locales/zh-cn.json
index 0acb816a1c..d3862795eb 100644
--- a/src/renderer/src/i18n/locales/zh-cn.json
+++ b/src/renderer/src/i18n/locales/zh-cn.json
@@ -3419,6 +3419,10 @@
           "help": "开启后备份时将跳过文件数据，仅备份配置信息，显著减小备份文件体积",
           "label": "精简备份"
         },
+        "bypassProxy": {
+          "help": "开启后，S3 请求将绕过应用程序代理，以防止大文件上传时的数据损坏。建议保持开启，除非您的 S3 端点需要通过代理访问。",
+          "label": "绕过代理"
+        },
         "syncStatus": {
           "error": "同步错误: {{message}}",
           "label": "同步状态",
diff --git a/src/renderer/src/i18n/locales/zh-tw.json b/src/renderer/src/i18n/locales/zh-tw.json
index 913a4de5ad..aa9d3f9a67 100644
--- a/src/renderer/src/i18n/locales/zh-tw.json
+++ b/src/renderer/src/i18n/locales/zh-tw.json
@@ -3419,6 +3419,10 @@
           "help": "開啟後備份時將跳過檔案資料，僅備份設定資訊，顯著減小備份檔案體積",
           "label": "精簡備份"
         },
+        "bypassProxy": {
+          "help": "開啟後，S3 請求將繞過應用程式代理，以防止大檔案上傳時的資料損壞。建議保持開啟，除非您的 S3 端點需要透過代理存取。",
+          "label": "繞過代理"
+        },
         "syncStatus": {
           "error": "同步錯誤: {{message}}",
           "label": "同步狀態",
diff --git a/src/renderer/src/pages/settings/DataSettings/S3Settings.tsx b/src/renderer/src/pages/settings/DataSettings/S3Settings.tsx
index fbb57cdec6..ec88266c03 100644
--- a/src/renderer/src/pages/settings/DataSettings/S3Settings.tsx
+++ b/src/renderer/src/pages/settings/DataSettings/S3Settings.tsx
@@ -31,7 +31,8 @@ const S3Settings: FC = () => {
     root: s3RootInit = '',
     syncInterval: s3SyncIntervalInit = 0,
     maxBackups: s3MaxBackupsInit = 5,
-    skipBackupFile: s3SkipBackupFileInit = false
+    skipBackupFile: s3SkipBackupFileInit = false,
+    bypassProxy: s3BypassProxyInit = true
   } = s3
 
   const [endpoint, setEndpoint] = useState<string | undefined>(s3EndpointInit)
@@ -41,6 +42,7 @@ const S3Settings: FC = () => {
   const [secretAccessKey, setSecretAccessKey] = useState<string | undefined>(s3SecretAccessKeyInit)
   const [root, setRoot] = useState<string | undefined>(s3RootInit)
   const [skipBackupFile, setSkipBackupFile] = useState<boolean>(s3SkipBackupFileInit)
+  const [bypassProxy, setBypassProxy] = useState<boolean>(s3BypassProxyInit)
   const [backupManagerVisible, setBackupManagerVisible] = useState(false)
 
   const [syncInterval, setSyncInterval] = useState<number>(s3SyncIntervalInit)
@@ -82,6 +84,11 @@ const S3Settings: FC = () => {
     dispatch(setS3Partial({ skipBackupFile: value }))
   }
 
+  const onBypassProxyChange = (value: boolean) => {
+    setBypassProxy(value)
+    dispatch(setS3Partial({ bypassProxy: value }))
+  }
+
   const renderSyncStatus = () => {
     if (!endpoint) return null
 
@@ -261,6 +268,14 @@ const S3Settings: FC = () => {
       <SettingRow>
         <SettingHelpText>{t('settings.data.s3.skipBackupFile.help')}</SettingHelpText>
       </SettingRow>
+      <SettingDivider />
+      <SettingRow>
+        <SettingRowTitle>{t('settings.data.s3.bypassProxy.label')}</SettingRowTitle>
+        <Switch checked={bypassProxy} onChange={onBypassProxyChange} />
+      </SettingRow>
+      <SettingRow>
+        <SettingHelpText>{t('settings.data.s3.bypassProxy.help')}</SettingHelpText>
+      </SettingRow>
       {syncInterval > 0 && (
         <>
           <SettingDivider />
diff --git a/src/renderer/src/store/settings.ts b/src/renderer/src/store/settings.ts
index 45f521b3df..c24a30d9e7 100644
--- a/src/renderer/src/store/settings.ts
+++ b/src/renderer/src/store/settings.ts
@@ -401,7 +401,8 @@ export const initialState: SettingsState = {
     autoSync: false,
     syncInterval: 0,
     maxBackups: 0,
-    skipBackupFile: false
+    skipBackupFile: false,
+    bypassProxy: true
   },
 
   // Developer mode
diff --git a/src/renderer/src/types/index.ts b/src/renderer/src/types/index.ts
index c86e80a157..7d2b5681ce 100644
--- a/src/renderer/src/types/index.ts
+++ b/src/renderer/src/types/index.ts
@@ -883,6 +883,7 @@ export type S3Config = {
   autoSync: boolean
   syncInterval: number
   maxBackups: number
+  bypassProxy?: boolean // Whether to bypass proxy for S3 requests (default: true)
 }
 
 export type { Message } from './newMessage'