diff --git a/.changeset/cuddly-flowers-provide.md b/.changeset/cuddly-flowers-provide.md
new file mode 100644
index 0000000000..729ac96cda
--- /dev/null
+++ b/.changeset/cuddly-flowers-provide.md
@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-fossa': patch
+---
+
+Allow configuration of base URL for Fossa links
diff --git a/plugins/fossa/README.md b/plugins/fossa/README.md
index 898c9d0475..10ccba5ba7 100644
--- a/plugins/fossa/README.md
+++ b/plugins/fossa/README.md
@@ -43,9 +43,12 @@ proxy:
     headers:
       Authorization: token ${FOSSA_API_TOKEN}
 
-# if you have a fossa organization, configure your id here
 fossa:
+  # if you have a fossa organization, configure your id here
   organizationId: <your-fossa-organization-id>
+  # if you have a self-managed fossa instance,
+  # configure the baseUrl to use for links to the fossa page here
+  externalLinkBaseUrl: <your fossa url>
 ```
 
 4. Get an api-token and provide `FOSSA_AUTH_HEADER` as env variable (https://app.fossa.com/account/settings/integrations/api_tokens)
diff --git a/plugins/fossa/config.d.ts b/plugins/fossa/config.d.ts
index 72d844c4e9..26a2823097 100644
--- a/plugins/fossa/config.d.ts
+++ b/plugins/fossa/config.d.ts
@@ -20,6 +20,12 @@ export interface Config {
      * The organization id in fossa.
      * @visibility frontend
      */
-    organizationId: string;
+    organizationId?: string;
+
+    /**
+     * The base url to use for external links (from Backstage to Fossa).
+     * @visibility frontend
+     */
+    externalLinkBaseUrl?: string;
   };
 }
diff --git a/plugins/fossa/src/api/FossaClient.test.ts b/plugins/fossa/src/api/FossaClient.test.ts
index 65b0fc1d53..0e2dc81e1f 100644
--- a/plugins/fossa/src/api/FossaClient.test.ts
+++ b/plugins/fossa/src/api/FossaClient.test.ts
@@ -175,6 +175,58 @@ describe('FossaClient', () => {
       expect(summary).toBeUndefined();
     });
 
+    it('should allow custom external link base url', async () => {
+      client = new FossaClient({
+        discoveryApi,
+        identityApi,
+        organizationId: '8736',
+        externalLinkBaseUrl: 'https://custom.fossa.com', // overrides the default app.fossa.com
+      });
+      server.use(
+        rest.get(`${mockBaseUrl}/fossa/projects`, (req, res, ctx) => {
+          const expectedQuery =
+            'count=1000&page=0&sort=title%2B&organizationId=8736&title=our-service';
+          if (req.url.searchParams.toString() !== expectedQuery) {
+            return res(
+              ctx.status(500),
+              ctx.body(
+                `${req.url.searchParams.toString()} !== ${expectedQuery}`,
+              ),
+            );
+          }
+
+          return res(
+            ctx.json([
+              {
+                locator: 'custom+8736/our-service',
+                title: 'our-service',
+                default_branch: 'develop',
+                revisions: [
+                  {
+                    updatedAt: '2020-01-01T00:00:00Z',
+                    dependency_count: 160,
+                    unresolved_licensing_issue_count: 5,
+                    unresolved_issue_count: 100,
+                  },
+                ],
+              },
+            ]),
+          );
+        }),
+      );
+
+      const summary = await client.getFindingSummary('our-service');
+
+      expect(summary).toEqual({
+        timestamp: '2020-01-01T00:00:00Z',
+        issueCount: 5,
+        dependencyCount: 160,
+        projectDefaultBranch: 'develop',
+        projectUrl:
+          'https://custom.fossa.com/projects/custom%2B8736%2Four-service',
+      } as FindingSummary);
+    });
+
     it('should handle 404 status', async () => {
       server.use(
         rest.get(`${mockBaseUrl}/fossa/projects`, (_req, res, ctx) => {
diff --git a/plugins/fossa/src/api/FossaClient.ts b/plugins/fossa/src/api/FossaClient.ts
index 66b44de21e..8b4b4b02e5 100644
--- a/plugins/fossa/src/api/FossaClient.ts
+++ b/plugins/fossa/src/api/FossaClient.ts
@@ -36,20 +36,24 @@ export class FossaClient implements FossaApi {
   discoveryApi: DiscoveryApi;
   identityApi: IdentityApi;
   organizationId?: string;
+  externalLinkBaseUrl: string;
   private readonly limit = pLimit(5);
 
   constructor({
     discoveryApi,
     identityApi,
     organizationId,
+    externalLinkBaseUrl = 'https://app.fossa.com',
   }: {
     discoveryApi: DiscoveryApi;
     identityApi: IdentityApi;
     organizationId?: string;
+    externalLinkBaseUrl?: string;
   }) {
     this.discoveryApi = discoveryApi;
     this.identityApi = identityApi;
     this.organizationId = organizationId;
+    this.externalLinkBaseUrl = externalLinkBaseUrl;
   }
 
   private async callApi<T>(
@@ -104,9 +108,9 @@ export class FossaClient implements FossaApi {
                 revision.unresolved_issue_count,
               dependencyCount: revision.dependency_count,
               projectDefaultBranch: project.default_branch,
-              projectUrl: `https://app.fossa.com/projects/${encodeURIComponent(
-                project.locator,
-              )}`,
+              projectUrl: `${
+                this.externalLinkBaseUrl
+              }/projects/${encodeURIComponent(project.locator)}`,
             },
           };
         }
diff --git a/plugins/fossa/src/plugin.ts b/plugins/fossa/src/plugin.ts
index a586d6d8a6..954ecedc81 100644
--- a/plugins/fossa/src/plugin.ts
+++ b/plugins/fossa/src/plugin.ts
@@ -39,6 +39,9 @@ export const fossaPlugin = createPlugin({
           discoveryApi,
           identityApi,
           organizationId: configApi.getOptionalString('fossa.organizationId'),
+          externalLinkBaseUrl: configApi.getOptionalString(
+            'fossa.externalLinkBaseUrl',
+          ),
         }),
     }),
   ],