diff --git a/src/components/structures/auth/CompleteSecurity.js b/src/components/structures/auth/CompleteSecurity.js
index 49fcf20415..2c46fe9823 100644
--- a/src/components/structures/auth/CompleteSecurity.js
+++ b/src/components/structures/auth/CompleteSecurity.js
@@ -28,6 +28,7 @@ import {
 } from '../../../stores/SetupEncryptionStore';
 import SetupEncryptionBody from "./SetupEncryptionBody";
 import {replaceableComponent} from "../../../utils/replaceableComponent";
+import SecurityCustomisations from "../../../customisations/Security";
 
 @replaceableComponent("structures.auth.CompleteSecurity")
 export default class CompleteSecurity extends React.Component {
@@ -45,6 +46,13 @@ export default class CompleteSecurity extends React.Component {
 
     _onStoreUpdate = () => {
         const store = SetupEncryptionStore.sharedInstance();
+
+        // Skip "you're done" phase if the UI isn't shown
+        if (store.phase === PHASE_DONE && SecurityCustomisations.SHOW_ENCRYPTION_SETUP_UI === false) {
+            this.props.onFinished(true);
+            return;
+        }
+
         this.setState({phase: store.phase});
     };
 
@@ -61,7 +69,9 @@ export default class CompleteSecurity extends React.Component {
         let icon;
         let title;
 
-        if (phase === PHASE_LOADING) {
+        // If the encryption UI is hidden then we can simply return nothing - the UI doesn't
+        // need to be running in order to set up encryption with the SecurityCustomisations.
+        if (phase === PHASE_LOADING || SecurityCustomisations.SHOW_ENCRYPTION_SETUP_UI === false) {
             return null;
         } else if (phase === PHASE_INTRO) {
             icon = <span className="mx_CompleteSecurity_headerIcon mx_E2EIcon_warning" />;
diff --git a/src/customisations/Security.ts b/src/customisations/Security.ts
index 96b5b62cdb..e215c5cb24 100644
--- a/src/customisations/Security.ts
+++ b/src/customisations/Security.ts
@@ -74,8 +74,20 @@ export interface ISecurityCustomisations {
     catchAccessSecretStorageError?: typeof catchAccessSecretStorageError,
     setupEncryptionNeeded?: typeof setupEncryptionNeeded,
     getDehydrationKey?: typeof getDehydrationKey,
+
+    /**
+     * When false, disables the post-login UI from showing. If there's
+     * an error during setup, that will be shown to the user.
+     *
+     * Note: when this is set to false then the app will assume the user's
+     * encryption is set up some other way which would circumvent the default
+     * UI, such as by presenting alternative UI.
+     */
+    SHOW_ENCRYPTION_SETUP_UI?: boolean, // default true
 }
 
 // A real customisation module will define and export one or more of the
 // customisation points that make up `ISecurityCustomisations`.
-export default {} as ISecurityCustomisations;
+export default {
+    SHOW_ENCRYPTION_SETUP_UI: true,
+} as ISecurityCustomisations;