diff --git a/lib/modules/datasource/custom/index.ts b/lib/modules/datasource/custom/index.ts
index 64d0fcfff9d757..80029a31e672f0 100644
--- a/lib/modules/datasource/custom/index.ts
+++ b/lib/modules/datasource/custom/index.ts
@@ -2,7 +2,7 @@ import is from '@sindresorhus/is';
 import jsonata from 'jsonata';
 import { logger } from '../../../logger';
 import { Datasource } from '../datasource';
-import type { GetReleasesConfig, ReleaseResult } from '../types';
+import type { DigestConfig, GetReleasesConfig, ReleaseResult } from '../types';
 import { fetchers } from './formats';
 import { ReleaseResultZodSchema } from './schema';
 import { getCustomConfig } from './utils';
@@ -57,4 +57,14 @@ export class CustomDatasource extends Datasource {
       return null;
     }
   }
+
+  override getDigest(
+    { packageName: repo, registryUrl }: Partial<DigestConfig>,
+    newValue?: string,
+  ): Promise<string | null> {
+    // Return null here to support setting a digest: value can be provided digest in getReleases
+    return new Promise<null>((resolve) => {
+      resolve(null);
+    });
+  }
 }
diff --git a/lib/workers/repository/process/lookup/__snapshots__/index.spec.ts.snap b/lib/workers/repository/process/lookup/__snapshots__/index.spec.ts.snap
index ec745fa6955e38..b9ae40694fc1dc 100644
--- a/lib/workers/repository/process/lookup/__snapshots__/index.spec.ts.snap
+++ b/lib/workers/repository/process/lookup/__snapshots__/index.spec.ts.snap
@@ -91,6 +91,22 @@ exports[`workers/repository/process/lookup/index .lookupUpdates() handles digest
 }
 `;
 
+exports[`workers/repository/process/lookup/index .lookupUpdates() handles digest update for custom datasource 1`] = `
+{
+  "currentVersion": "1.0.0",
+  "fixedVersion": "1.0.0",
+  "updates": [
+    {
+      "newDigest": "0123456789abcdef",
+      "newValue": "1.0.0",
+      "updateType": "digest",
+    },
+  ],
+  "versioning": "npm",
+  "warnings": [],
+}
+`;
+
 exports[`workers/repository/process/lookup/index .lookupUpdates() handles digest update for non-version 1`] = `
 {
   "updates": [
diff --git a/lib/workers/repository/process/lookup/index.spec.ts b/lib/workers/repository/process/lookup/index.spec.ts
index e9001458c7177b..fbff03858b3ddb 100644
--- a/lib/workers/repository/process/lookup/index.spec.ts
+++ b/lib/workers/repository/process/lookup/index.spec.ts
@@ -4,6 +4,7 @@ import * as httpMock from '../../../../../test/http-mock';
 import { partial } from '../../../../../test/util';
 import { getConfig } from '../../../../config/defaults';
 import { CONFIG_VALIDATION } from '../../../../constants/error-messages';
+import { CustomDatasource } from '../../../../modules/datasource/custom';
 import { DockerDatasource } from '../../../../modules/datasource/docker';
 import { GitRefsDatasource } from '../../../../modules/datasource/git-refs';
 import { GithubReleasesDatasource } from '../../../../modules/datasource/github-releases';
@@ -56,6 +57,11 @@ describe('workers/repository/process/lookup/index', () => {
     'getReleases',
   );
 
+  const getCustomDatasourceReleases = jest.spyOn(
+    CustomDatasource.prototype,
+    'getReleases',
+  );
+
   const getDockerDigest = jest.spyOn(DockerDatasource.prototype, 'getDigest');
 
   beforeEach(() => {
@@ -1938,6 +1944,31 @@ describe('workers/repository/process/lookup/index', () => {
       });
     });
 
+    it('handles digest update for custom datasource', async () => {
+      config.currentValue = '1.0.0';
+      config.packageName = 'my-package';
+      config.datasource = CustomDatasource.id;
+      config.currentDigest = 'zzzzzzzzzzzzzzz';
+      getCustomDatasourceReleases.mockResolvedValueOnce({
+        releases: [
+          {
+            version: '1.0.0',
+            newDigest: '0123456789abcdef',
+          },
+        ],
+      });
+      const res = await lookup.lookupUpdates(config);
+      expect(res).toMatchSnapshot({
+        updates: [
+          {
+            newDigest: '0123456789abcdef',
+            newValue: '1.0.0',
+            updateType: 'digest',
+          },
+        ],
+      });
+    });
+
     it('handles digest update for non-version', async () => {
       config.currentValue = 'alpine';
       config.packageName = 'node';