diff --git a/CHANGELOG.md b/CHANGELOG.md
index e608aff..324b2ca 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Consistent IPFS gateway URL normalization in `IPFSStorage.upload` (#504)
+
+- Issue #504: Factored gateway URL normalization out of `IPFSStorage.resolve` into a shared helper used by both `upload()` and `resolve()` so custom gateways without an `/ipfs` suffix return consistent gateway URLs.
+
 ### MultiSigConfig integration (#442)
 
 - Issue #442: Established `InitMultiSigParams extends MultiSigConfig`, added `MultiSigEscrowClient.getConfig` to expose operation configuration, and added integration tests.
diff --git a/src/storage/ipfs.ts b/src/storage/ipfs.ts
index 0e178ab..a3ea347 100644
--- a/src/storage/ipfs.ts
+++ b/src/storage/ipfs.ts
@@ -60,6 +60,15 @@ export interface IPFSResolveOptions {
   timeoutMs?: number;
 }
 
+function normalizeGatewayUrl(gateway: string): string {
+  const cleanGateway = gateway.replace(/\/+$/, '');
+  return /\/ipfs(?:\/|$)/.test(cleanGateway) ? cleanGateway : `${cleanGateway}/ipfs`;
+}
+
+function buildGatewayCidUrl(gateway: string, cid: string): string {
+  return `${normalizeGatewayUrl(gateway)}/${cid}`;
+}
+
 /**
  * IPFS storage helper — uploads files and resolves JSON metadata with automatic gateway fallback.
  */
@@ -130,7 +139,7 @@ export class IPFSStorage {
         return { ok: false, error: 'Upload succeeded but response did not include a valid CID' };
       }
       logger.info('IPFS upload succeeded', { cid });
-      return { ok: true, data: { cid, url: `${this.gatewayUrl}/${cid}` } };
+      return { ok: true, data: { cid, url: buildGatewayCidUrl(this.gatewayUrl, cid) } };
     } catch (err) {
       logger.error('IPFS upload failed', { error: toApiErrorMessage(err) });
       return { ok: false, error: toApiErrorMessage(err) };
@@ -158,8 +167,7 @@ export class IPFSStorage {
 
     for (const gateway of this.gateways) {
       const cleanGateway = gateway.replace(/\/+$/, '');
-      const baseUrl = cleanGateway.includes('/ipfs') ? cleanGateway : `${cleanGateway}/ipfs`;
-      const url = `${baseUrl}/${cid}`;
+      const url = buildGatewayCidUrl(cleanGateway, cid);
       try {
         logger.debug('Resolving IPFS CID from gateway', { gateway: cleanGateway, cid });
         const response = await axios.get(url, {
diff --git a/tests/storage.test.ts b/tests/storage.test.ts
index bdef7a5..d283b59 100644
--- a/tests/storage.test.ts
+++ b/tests/storage.test.ts
@@ -164,4 +164,38 @@ describe('IPFSStorage.upload', () => {
       expect(result.error).toMatch(/Network error/);
     }
   });
+
+  it('normalizes custom gatewayUrl without /ipfs so upload() matches resolve() URL construction (#504)', async () => {
+    const axios = jest.requireActual('axios');
+    const getSpy = jest.spyOn(axios, 'get').mockResolvedValue({
+      status: 200,
+      headers: { 'content-type': 'application/json' },
+      data: '{"ok":true}',
+    });
+    const validCid = 'QmYwAPJzv5CZsnA625s3Xf2nemtYgPpHdWEz79ojWnPbdG';
+
+    try {
+      for (const [gatewayUrl, expectedPrefix] of [
+        ['https://my-gateway.example', 'https://my-gateway.example/ipfs'],
+        ['https://my-gateway.example/', 'https://my-gateway.example/ipfs'],
+        ['https://my-gateway.example/ipfs/', 'https://my-gateway.example/ipfs'],
+        ['https://my-gateway.example/ipfs-proxy', 'https://my-gateway.example/ipfs-proxy/ipfs'],
+      ] as const) {
+        getSpy.mockClear();
+        mockHttpPost.mockResolvedValueOnce({ data: { cid: validCid } });
+
+        const storage = new IPFSStorage({ gatewayUrl });
+        const uploadResult = await storage.upload(Buffer.from('payload'));
+        await storage.resolve(validCid);
+
+        expect(uploadResult.ok).toBe(true);
+        if (uploadResult.ok) {
+          expect(uploadResult.data.url).toBe(`${expectedPrefix}/${validCid}`);
+          expect(getSpy).toHaveBeenCalledWith(uploadResult.data.url, expect.any(Object));
+        }
+      }
+    } finally {
+      getSpy.mockRestore();
+    }
+  });
 });