diff --git a/packages/backend-common/src/discovery/HostDiscovery.test.ts b/packages/backend-common/src/discovery/HostDiscovery.test.ts
index 381acbde19..577da3a679 100644
--- a/packages/backend-common/src/discovery/HostDiscovery.test.ts
+++ b/packages/backend-common/src/discovery/HostDiscovery.test.ts
@@ -207,4 +207,33 @@ describe('HostDiscovery', () => {
       'http://scaffolder-external:8080/api/scaffolder',
     );
   });
+
+  it('encodes the pluginId', async () => {
+    const discovery = HostDiscovery.fromConfig(
+      new ConfigReader({
+        backend: {
+          baseUrl: 'http://localhost:40',
+          listen: { port: 80, host: 'localhost' },
+        },
+        discovery: {
+          endpoints: [
+            {
+              target: 'http://common-backend:8080/api/{{pluginId}}',
+              plugins: ['plugin/beta'],
+            },
+          ],
+        },
+      }),
+    );
+
+    await expect(discovery.getBaseUrl('plugin/beta')).resolves.toBe(
+      'http://common-backend:8080/api/plugin%2Fbeta',
+    );
+    await expect(discovery.getBaseUrl('plugin/alpha')).resolves.toBe(
+      'http://localhost:80/api/plugin%2Falpha',
+    );
+    await expect(discovery.getExternalBaseUrl('plugin/alpha')).resolves.toBe(
+      'http://localhost:40/api/plugin%2Falpha',
+    );
+  });
 });
diff --git a/packages/backend-common/src/discovery/HostDiscovery.ts b/packages/backend-common/src/discovery/HostDiscovery.ts
index 83def76aae..87089a0895 100644
--- a/packages/backend-common/src/discovery/HostDiscovery.ts
+++ b/packages/backend-common/src/discovery/HostDiscovery.ts
@@ -37,7 +37,7 @@ export class HostDiscovery implements PluginEndpointDiscovery {
    * discovering the external URL, and the `.listen` and `.https` config
    * for the internal one.
    *
-   * Can be overridden by in config by providing a target and corresponding plugin in `discovery.endpoint`.
+   * Can be overridden in config by providing a target and corresponding plugins in `discovery.endpoint`.
    * eg.
    * ```yaml
    * discovery:
@@ -101,34 +101,31 @@ export class HostDiscovery implements PluginEndpointDiscovery {
       ?.get<Target>('target');
 
     if (!target) {
-      return null;
+      const baseUrl =
+        type === 'external' ? this.externalBaseUrl : this.internalBaseUrl;
+
+      return `${baseUrl}/${encodeURIComponent(pluginId)}`;
     }
 
     if (typeof target === 'string') {
-      return target.replace(/\{\{\s*pluginId\s*\}\}/, pluginId);
+      return target.replace(
+        /\{\{\s*pluginId\s*\}\}/g,
+        encodeURIComponent(pluginId),
+      );
     }
 
-    return target[type].replace(/\{\{\s*pluginId\s*\}\}/, pluginId);
+    return target[type].replace(
+      /\{\{\s*pluginId\s*\}\}/g,
+      encodeURIComponent(pluginId),
+    );
   }
 
   async getBaseUrl(pluginId: string): Promise<string> {
-    const target = this.getTargetFromConfig(pluginId, 'internal');
-
-    if (target) {
-      return target;
-    }
-
-    return `${this.internalBaseUrl}/${pluginId}`;
+    return this.getTargetFromConfig(pluginId, 'internal');
   }
 
   async getExternalBaseUrl(pluginId: string): Promise<string> {
-    const target = this.getTargetFromConfig(pluginId, 'external');
-
-    if (target) {
-      return target;
-    }
-
-    return `${this.externalBaseUrl}/${pluginId}`;
+    return this.getTargetFromConfig(pluginId, 'external');
   }
 }