diff --git a/apps/portal/src/app/features/vessel-transfer/mock.ts b/apps/portal/src/app/features/vessel-transfer/mock.ts
index b7d6aacfa..6281c923e 100644
--- a/apps/portal/src/app/features/vessel-transfer/mock.ts
+++ b/apps/portal/src/app/features/vessel-transfer/mock.ts
@@ -44,6 +44,7 @@ export interface TransferRequest {
   submitted: string;
   approvedOn?: string;
   rejectionReason?: string;
+  documentFileInfo?: unknown;
 }
 
 export const MOCK_REQUESTS: TransferRequest[] = [
diff --git a/apps/portal/src/app/features/vessel-transfer/pages/VesselTransferApplicationPage.tsx b/apps/portal/src/app/features/vessel-transfer/pages/VesselTransferApplicationPage.tsx
index d79fc2abc..1f2ad69b9 100644
--- a/apps/portal/src/app/features/vessel-transfer/pages/VesselTransferApplicationPage.tsx
+++ b/apps/portal/src/app/features/vessel-transfer/pages/VesselTransferApplicationPage.tsx
@@ -18,6 +18,7 @@ import {
 } from '@mantine/core';
 import { IconArrowLeft, IconArrowRight, IconCheck, IconInfoCircle, IconUpload } from '@tabler/icons-react';
 import { notify } from '@ema-platform/ui';
+import { isStorageUploadError, useDocumentUpload } from '@ema-platform/api';
 import { addTransferRequest, MOCK_VESSELS, TRANSFER_REASONS } from '../mock';
 import { useAppSelector } from '../../../store/hooks';
 
@@ -45,22 +46,31 @@ export function VesselTransferApplicationPage() {
   const [reason, setReason] = useState<string | null>(null);
   const [document, setDocument] = useState<File | null>(null);
 
+  const { upload, isUploading } = useDocumentUpload();
+
   const step0Ok = !!vessel;
   const step1Ok = !!newOwnerName && !!newOwnerIdOrTin && !!newOwnerPhone
     && EMAIL_RE.test(newOwnerEmail) && !!newOwnerAddress;
   const step2Ok = !!reason && !!document;
 
-  const handleSubmit = () => {
-    if (!vessel || !reason) return;
-    addTransferRequest({
-      vesselName: vessel.name,
-      vesselRegNo: vessel.regNo,
-      currentOwner,
-      newOwnerName,
-      reason: reason as (typeof TRANSFER_REASONS)[number],
-    });
-    notify.success('Transfer request submitted. SMS and email confirmation sent.');
-    navigate('/vessel-transfers');
+  const handleSubmit = async () => {
+    if (!vessel || !reason || !document) return;
+    try {
+      const { fileInfo } = await upload(document, '/documents/get-file-upload-key');
+      addTransferRequest({
+        vesselName: vessel.name,
+        vesselRegNo: vessel.regNo,
+        currentOwner,
+        newOwnerName,
+        reason: reason as (typeof TRANSFER_REASONS)[number],
+        documentFileInfo: fileInfo,
+      });
+      notify.success('Transfer request submitted. SMS and email confirmation sent.');
+      navigate('/vessel-transfers');
+    } catch (error) {
+      const tooLarge = isStorageUploadError(error) && error.message === 'STORAGE_UPLOAD_TOO_LARGE';
+      notify.error(tooLarge ? 'File is too large to upload.' : 'Failed to upload document. Please try again.');
+    }
   };
 
   return (
@@ -189,7 +199,7 @@ export function VesselTransferApplicationPage() {
             Next
           </Button>
         ) : (
-          <Button color="teal" leftSection={<IconCheck size={14} />} onClick={handleSubmit}>
+          <Button color="teal" leftSection={<IconCheck size={14} />} onClick={handleSubmit} loading={isUploading}>
             Submit Request
           </Button>
         )}
diff --git a/libs/api/src/index.ts b/libs/api/src/index.ts
index b24880dd7..ff1fd4761 100644
--- a/libs/api/src/index.ts
+++ b/libs/api/src/index.ts
@@ -1,4 +1,5 @@
 export * from './lib/base-api';
 export * from './lib/query-and-mutation';
 export * from './lib/session';
+export * from './lib/file-upload';
 export { baseQueryWithReauth, configureTokenRefresh } from './lib/base-api/base-query-with-reauth';
diff --git a/libs/api/src/lib/file-upload/index.ts b/libs/api/src/lib/file-upload/index.ts
new file mode 100644
index 000000000..ff7b2c2be
--- /dev/null
+++ b/libs/api/src/lib/file-upload/index.ts
@@ -0,0 +1,87 @@
+import { useCallback, useState } from 'react';
+import { baseApi } from '../base-api';
+import { resolveTokenFromStorage } from '../session';
+
+export interface UploadKeyResponse<TFileInfo = unknown> {
+  presigned: string;
+  fileInfo: TFileInfo;
+}
+
+const fileUploadApi = baseApi.injectEndpoints({
+  endpoints: (builder) => ({
+    getFileUploadKey: builder.mutation<UploadKeyResponse, { endpoint: string; file: File }>({
+      query: ({ endpoint, file }) => ({
+        url: endpoint,
+        method: 'POST',
+        body: {
+          fileName: file.name,
+          contentType: file.type || 'application/octet-stream',
+          size: file.size,
+          originalname: file.name,
+        },
+      }),
+    }),
+  }),
+  overrideExisting: false,
+});
+
+export const { useGetFileUploadKeyMutation } = fileUploadApi;
+
+export const STORAGE_UPLOAD_ERROR = 'STORAGE_UPLOAD_ERROR';
+export const STORAGE_UPLOAD_TOO_LARGE = 'STORAGE_UPLOAD_TOO_LARGE';
+
+export function isStorageUploadError(
+  error: unknown,
+): error is Error & { message: typeof STORAGE_UPLOAD_ERROR | typeof STORAGE_UPLOAD_TOO_LARGE } {
+  return (
+    error instanceof Error &&
+    (error.message === STORAGE_UPLOAD_ERROR || error.message === STORAGE_UPLOAD_TOO_LARGE)
+  );
+}
+
+// Bare fetch on purpose: this PUT targets the presigned storage URL directly, not
+// VITE_BASE_API_URL, so it must not go through baseApi/fetchBaseQuery.
+async function uploadToPresigned(file: File, presignedUrl: string): Promise<void> {
+  if (!presignedUrl) throw new Error(STORAGE_UPLOAD_ERROR);
+
+  const token = resolveTokenFromStorage();
+  const res = await fetch(presignedUrl, {
+    method: 'PUT',
+    body: file,
+    headers: {
+      'Content-Type': file.type || 'application/octet-stream',
+      ...(token ? { Authorization: `Bearer ${token}` } : {}),
+    },
+  });
+
+  if (res.status === 413) throw new Error(STORAGE_UPLOAD_TOO_LARGE);
+  if (!res.ok) throw new Error(STORAGE_UPLOAD_ERROR);
+}
+
+export function useDocumentUpload() {
+  const [getFileUploadKey, mutationState] = useGetFileUploadKeyMutation();
+  // Spans both steps (key request + presigned PUT) — mutationState.isLoading alone
+  // would drop to false once the key request resolves, before the file PUT finishes.
+  const [isUploading, setIsUploading] = useState(false);
+
+  const upload = useCallback(
+    async <TFileInfo = unknown>(file: File, endpoint: string): Promise<UploadKeyResponse<TFileInfo>> => {
+      setIsUploading(true);
+      try {
+        const { presigned, fileInfo } = await getFileUploadKey({ endpoint, file }).unwrap();
+        await uploadToPresigned(file, presigned);
+        return { presigned, fileInfo: fileInfo as TFileInfo };
+      } finally {
+        setIsUploading(false);
+      }
+    },
+    [getFileUploadKey],
+  );
+
+  return {
+    upload,
+    isUploading,
+    error: mutationState.error,
+    reset: mutationState.reset,
+  };
+}