diff --git a/.changeset/shy-buckets-knock.md b/.changeset/shy-buckets-knock.md
new file mode 100644
index 00000000..1e0e5d41
--- /dev/null
+++ b/.changeset/shy-buckets-knock.md
@@ -0,0 +1,5 @@
+---
+"@tus/s3-store": minor
+---
+
+Add `s3Client` option. This allows user to provide existing S3 client to datastore.
diff --git a/packages/s3-store/README.md b/packages/s3-store/README.md
index d2f30883..9d659035 100644
--- a/packages/s3-store/README.md
+++ b/packages/s3-store/README.md
@@ -91,6 +91,10 @@ Options to pass to the AWS S3 SDK. Checkout the
 docs for the supported options. You need to at least set the `region`, `bucket` name, and
 your preferred method of authentication.
 
+### `options.s3Client`
+
+Option to pass existing instance of S3 client that should be used. This option has priority over `options.s3ClientConfig`, but you still need to use `options.s3ClientConfig` to set `bucket` name.
+
 #### `options.expirationPeriodInMilliseconds`
 
 Enables the expiration extension and sets the expiration period of an upload url in
diff --git a/packages/s3-store/src/index.ts b/packages/s3-store/src/index.ts
index 40e1367c..15c83d16 100644
--- a/packages/s3-store/src/index.ts
+++ b/packages/s3-store/src/index.ts
@@ -47,6 +47,7 @@ export type Options = {
   expirationPeriodInMilliseconds?: number
   // Options to pass to the AWS S3 SDK.
   s3ClientConfig: S3ClientConfig & {bucket: string}
+  s3Client?: AWS.S3
 }
 
 export type MetadataValue = {
@@ -127,7 +128,7 @@ export class S3Store extends DataStore {
     this.expirationPeriodInMilliseconds = options.expirationPeriodInMilliseconds ?? 0
     this.useTags = options.useTags ?? true
     this.cache = options.cache ?? new MemoryKvStore<MetadataValue>()
-    this.client = new S3(restS3ClientConfig)
+    this.client = options.s3Client ?? new S3(restS3ClientConfig)
     this.partUploadSemaphore = new Semaphore(options.maxConcurrentPartUploads ?? 60)
   }
 
diff --git a/packages/s3-store/test/index.ts b/packages/s3-store/test/index.ts
index 4a8e31af..80a13fd2 100644
--- a/packages/s3-store/test/index.ts
+++ b/packages/s3-store/test/index.ts
@@ -3,6 +3,7 @@ import assert from 'node:assert/strict'
 import {Readable} from 'node:stream'
 
 import sinon from 'sinon'
+import { S3 } from '@aws-sdk/client-s3'
 
 import {S3Store} from '../src'
 import * as shared from 'test/stores.test'
@@ -294,6 +295,25 @@ describe('S3DataStore', () => {
     assert.equal(store.maxMultipartParts, customMaxParts)
   })
 
+  it('should use custom S3 client when specified', async () => {
+    const client = new S3(s3ClientConfig);
+    const store = new S3Store({
+      s3Client: client,
+      s3ClientConfig,
+    });
+
+    const clientMock = sinon.mock(client);
+    clientMock.expects("putObject").once();
+
+    await store.create(new Upload({
+      id: shared.testId('test-upload'),
+      size: 10 * 1024 * 1024,
+      offset: 0,
+    }))
+
+    clientMock.verify();
+  })
+
   shared.shouldHaveStoreMethods()
   shared.shouldCreateUploads()
   shared.shouldRemoveUploads() // Termination extension