diff --git a/.changeset/fifty-horses-battle.md b/.changeset/fifty-horses-battle.md
new file mode 100644
index 0000000000..c7164c7309
--- /dev/null
+++ b/.changeset/fifty-horses-battle.md
@@ -0,0 +1,24 @@
+---
+'@backstage/core-plugin-api': minor
+---
+
+Removed deprecated `IdentityApi` methods: `getUserId`, `getIdToken`, and `getProfile`.
+
+Existing usage of `getUserId` can be replaced by `getBackstageIdentity`, more precisely the equivalent of the previous `userId` can be retrieved like this:
+
+```ts
+import { parseEntityRef } from '@backstage/catalog-model';
+
+const identity = await identityApi.getBackstageIdentity();
+const { name: userId } = parseEntityRef(identity.userEntityRef);
+```
+
+Note that it is recommended to consume the entire `userEntityRef` rather than parsing out just the name, in order to support namespaces.
+
+Existing usage of `getIdToken` can be replaced by `getCredentials`, like this:
+
+```ts
+const { token } = await identityApi.getCredentials();
+```
+
+And existing usage of `getProfile` is replaced by `getProfileInfo`, which returns the same profile object, but is now async.
diff --git a/.changeset/mean-rings-burn.md b/.changeset/mean-rings-burn.md
new file mode 100644
index 0000000000..2996de5c72
--- /dev/null
+++ b/.changeset/mean-rings-burn.md
@@ -0,0 +1,6 @@
+---
+'@backstage/core-app-api': minor
+'@backstage/core-plugin-api': minor
+---
+
+Removed deprecated `SignInResult` type, which was replaced with the new `onSignInSuccess` callback.
diff --git a/packages/core-app-api/api-report.md b/packages/core-app-api/api-report.md
index af25679878..cc38618a00 100644
--- a/packages/core-app-api/api-report.md
+++ b/packages/core-app-api/api-report.md
@@ -563,14 +563,6 @@ export type SignInPageProps = {
   onSignInSuccess(identityApi: IdentityApi): void;
 };
 
-// @public @deprecated
-export type SignInResult = {
-  userId: string;
-  profile: ProfileInfo;
-  getIdToken?: () => Promise<string>;
-  signOut?: () => Promise<void>;
-};
-
 // @public
 export class UnhandledErrorForwarder {
   static forward(errorApi: ErrorApi, errorContext: ErrorApiErrorContext): void;
diff --git a/packages/core-app-api/src/apis/implementations/IdentityApi/AppIdentityProxy.ts b/packages/core-app-api/src/apis/implementations/IdentityApi/AppIdentityProxy.ts
index 8a2f12594c..6868ebe265 100644
--- a/packages/core-app-api/src/apis/implementations/IdentityApi/AppIdentityProxy.ts
+++ b/packages/core-app-api/src/apis/implementations/IdentityApi/AppIdentityProxy.ts
@@ -26,15 +26,30 @@ function mkError(thing: string) {
   );
 }
 
+function logDeprecation(thing: string) {
+  // eslint-disable-next-line no-console
+  console.warn(
+    `WARNING: Call to ${thing} is deprecated and will break in the future`,
+  );
+}
+
+// We use this for a period of backwards compatibility. It is a hidden
+// compatibility that will allow old plugins to continue working for a limited time.
+type CompatibilityIdentityApi = IdentityApi & {
+  getUserId?(): string;
+  getIdToken?(): Promise<string | undefined>;
+  getProfile?(): ProfileInfo;
+};
+
 /**
  * Implementation of the connection between the App-wide IdentityApi
  * and sign-in page.
  */
 export class AppIdentityProxy implements IdentityApi {
-  private target?: IdentityApi;
+  private target?: CompatibilityIdentityApi;
 
   // This is called by the app manager once the sign-in page provides us with an implementation
-  setTarget(identityApi: IdentityApi) {
+  setTarget(identityApi: CompatibilityIdentityApi) {
     this.target = identityApi;
   }
 
@@ -42,6 +57,10 @@ export class AppIdentityProxy implements IdentityApi {
     if (!this.target) {
       throw mkError('getUserId');
     }
+    if (!this.target.getUserId) {
+      throw new Error('IdentityApi does not implement getUserId');
+    }
+    logDeprecation('getUserId');
     return this.target.getUserId();
   }
 
@@ -49,6 +68,10 @@ export class AppIdentityProxy implements IdentityApi {
     if (!this.target) {
       throw mkError('getProfile');
     }
+    if (!this.target.getProfile) {
+      throw new Error('IdentityApi does not implement getProfile');
+    }
+    logDeprecation('getProfile');
     return this.target.getProfile();
   }
 
@@ -77,6 +100,10 @@ export class AppIdentityProxy implements IdentityApi {
     if (!this.target) {
       throw mkError('getIdToken');
     }
+    if (!this.target.getIdToken) {
+      throw new Error('IdentityApi does not implement getIdToken');
+    }
+    logDeprecation('getIdToken');
     return this.target.getIdToken();
   }
 
diff --git a/packages/core-app-api/src/app/types.ts b/packages/core-app-api/src/app/types.ts
index bacaf83fbd..902e64c09f 100644
--- a/packages/core-app-api/src/app/types.ts
+++ b/packages/core-app-api/src/app/types.ts
@@ -18,7 +18,6 @@ import { ComponentType } from 'react';
 import {
   AnyApiFactory,
   AppTheme,
-  ProfileInfo,
   IconComponent,
   BackstagePlugin,
   RouteRef,
@@ -38,31 +37,6 @@ export type BootErrorPageProps = {
   error: Error;
 };
 
-/**
- * The outcome of signing in on the sign-in page.
- *
- * @public
- * @deprecated replaced by passing the {@link @backstage/core-plugin-api#IdentityApi} to the {@link SignInPageProps.onSignInSuccess} instead.
- */
-export type SignInResult = {
-  /**
-   * User ID that will be returned by the IdentityApi
-   */
-  userId: string;
-
-  profile: ProfileInfo;
-
-  /**
-   * Function used to retrieve an ID token for the signed in user.
-   */
-  getIdToken?: () => Promise<string>;
-
-  /**
-   * Sign out handler that will be called if the user requests to sign out.
-   */
-  signOut?: () => Promise<void>;
-};
-
 /**
  * Props for the `SignInPage` component of {@link AppComponents}.
  *
diff --git a/packages/core-components/api-report.md b/packages/core-components/api-report.md
index 29847b079e..070131af96 100644
--- a/packages/core-components/api-report.md
+++ b/packages/core-components/api-report.md
@@ -38,7 +38,6 @@ import { ReactElement } from 'react';
 import { ReactNode } from 'react';
 import { SessionApi } from '@backstage/core-plugin-api';
 import { SignInPageProps } from '@backstage/core-plugin-api';
-import { SignInResult } from '@backstage/core-plugin-api';
 import { SparklinesLineProps } from 'react-sparklines';
 import { SparklinesProps } from 'react-sparklines';
 import { StyledComponentProps } from '@material-ui/core/styles';
@@ -2395,7 +2394,12 @@ export class UserIdentity implements IdentityApi {
     profile?: ProfileInfo;
   }): IdentityApi;
   static createGuest(): IdentityApi;
-  static fromLegacy(result: SignInResult): IdentityApi;
+  static fromLegacy(result: {
+    userId: string;
+    profile: ProfileInfo;
+    getIdToken?: () => Promise<string>;
+    signOut?: () => Promise<void>;
+  }): IdentityApi;
   // (undocumented)
   getBackstageIdentity(): Promise<BackstageUserIdentity>;
   // (undocumented)
diff --git a/packages/core-components/src/layout/SignInPage/IdentityApiSignOutProxy.ts b/packages/core-components/src/layout/SignInPage/IdentityApiSignOutProxy.ts
index ec45bc7399..396913b9b7 100644
--- a/packages/core-components/src/layout/SignInPage/IdentityApiSignOutProxy.ts
+++ b/packages/core-components/src/layout/SignInPage/IdentityApiSignOutProxy.ts
@@ -20,30 +20,46 @@ import {
   ProfileInfo,
 } from '@backstage/core-plugin-api';
 
+// Similar to the AppIdentityApi we provide backwards compatibility for a limited time
+type CompatibilityIdentityApi = IdentityApi & {
+  getUserId?(): string;
+  getIdToken?(): Promise<string | undefined>;
+  getProfile?(): ProfileInfo;
+};
+
 export class IdentityApiSignOutProxy implements IdentityApi {
   private constructor(
     private readonly config: {
-      identityApi: IdentityApi;
+      identityApi: CompatibilityIdentityApi;
       signOut: IdentityApi['signOut'];
     },
   ) {}
 
   static from(config: {
-    identityApi: IdentityApi;
+    identityApi: CompatibilityIdentityApi;
     signOut: IdentityApi['signOut'];
   }): IdentityApi {
     return new IdentityApiSignOutProxy(config);
   }
 
   getUserId(): string {
+    if (!this.config.identityApi.getUserId) {
+      throw new Error(`SignOutProxy IdentityApi.getUserId is not implemented`);
+    }
     return this.config.identityApi.getUserId();
   }
 
   getIdToken(): Promise<string | undefined> {
+    if (!this.config.identityApi.getIdToken) {
+      throw new Error(`SignOutProxy IdentityApi.getIdToken is not implemented`);
+    }
     return this.config.identityApi.getIdToken();
   }
 
   getProfile(): ProfileInfo {
+    if (!this.config.identityApi.getProfile) {
+      throw new Error(`SignOutProxy IdentityApi.getProfile is not implemented`);
+    }
     return this.config.identityApi.getProfile();
   }
 
diff --git a/packages/core-components/src/layout/SignInPage/LegacyUserIdentity.ts b/packages/core-components/src/layout/SignInPage/LegacyUserIdentity.ts
index e28f94072e..cc51d2b9a8 100644
--- a/packages/core-components/src/layout/SignInPage/LegacyUserIdentity.ts
+++ b/packages/core-components/src/layout/SignInPage/LegacyUserIdentity.ts
@@ -18,7 +18,6 @@ import {
   IdentityApi,
   ProfileInfo,
   BackstageUserIdentity,
-  SignInResult,
 } from '@backstage/core-plugin-api';
 
 function parseJwtPayload(token: string) {
@@ -26,14 +25,22 @@ function parseJwtPayload(token: string) {
   return JSON.parse(atob(payload));
 }
 
+type LegacySignInResult = {
+  userId: string;
+  profile: ProfileInfo;
+  getIdToken?: () => Promise<string>;
+  signOut?: () => Promise<void>;
+};
+
+/** @internal */
 export class LegacyUserIdentity implements IdentityApi {
-  private constructor(private readonly result: SignInResult) {}
+  private constructor(private readonly result: LegacySignInResult) {}
 
   getUserId(): string {
     return this.result.userId;
   }
 
-  static fromResult(result: SignInResult): LegacyUserIdentity {
+  static fromResult(result: LegacySignInResult): LegacyUserIdentity {
     return new LegacyUserIdentity(result);
   }
 
diff --git a/packages/core-components/src/layout/SignInPage/UserIdentity.ts b/packages/core-components/src/layout/SignInPage/UserIdentity.ts
index 7781c79154..781cb47c0e 100644
--- a/packages/core-components/src/layout/SignInPage/UserIdentity.ts
+++ b/packages/core-components/src/layout/SignInPage/UserIdentity.ts
@@ -21,12 +21,17 @@ import {
   BackstageUserIdentity,
   BackstageIdentityApi,
   SessionApi,
-  SignInResult,
 } from '@backstage/core-plugin-api';
 
 import { GuestUserIdentity } from './GuestUserIdentity';
 import { LegacyUserIdentity } from './LegacyUserIdentity';
 
+// TODO(Rugvip): This and the other IdentityApi implementations still implement
+//               the old removed methods. This is to allow for backwards compatibility
+//               with old plugins that still consume this API. We will leave these in
+//               place as a hidden compatibility for a couple of months.
+//               The AppIdentityProxy warns in case any of these methods are called.
+
 /**
  * An implementation of the IdentityApi that is constructed using
  * various backstage user identity representations.
@@ -49,7 +54,24 @@ export class UserIdentity implements IdentityApi {
    *
    * @public
    */
-  static fromLegacy(result: SignInResult): IdentityApi {
+  static fromLegacy(result: {
+    /**
+     * User ID that will be returned by the IdentityApi
+     */
+    userId: string;
+
+    profile: ProfileInfo;
+
+    /**
+     * Function used to retrieve an ID token for the signed in user.
+     */
+    getIdToken?: () => Promise<string>;
+
+    /**
+     * Sign out handler that will be called if the user requests to sign out.
+     */
+    signOut?: () => Promise<void>;
+  }): IdentityApi {
     return LegacyUserIdentity.fromResult(result);
   }
 
diff --git a/packages/core-plugin-api/api-report.md b/packages/core-plugin-api/api-report.md
index de25d24660..875c27dae9 100644
--- a/packages/core-plugin-api/api-report.md
+++ b/packages/core-plugin-api/api-report.md
@@ -12,7 +12,6 @@ import { IconComponent as IconComponent_2 } from '@backstage/core-plugin-api';
 import { IdentityApi as IdentityApi_2 } from '@backstage/core-plugin-api';
 import { JsonValue } from '@backstage/types';
 import { Observable } from '@backstage/types';
-import { ProfileInfo as ProfileInfo_2 } from '@backstage/core-plugin-api';
 import { default as React_2 } from 'react';
 import { ReactElement } from 'react';
 import { ReactNode } from 'react';
@@ -512,9 +511,6 @@ export type IconComponent = ComponentType<{
 
 // @public
 export type IdentityApi = {
-  getUserId(): string;
-  getIdToken(): Promise<string | undefined>;
-  getProfile(): ProfileInfo;
   getProfileInfo(): Promise<ProfileInfo>;
   getBackstageIdentity(): Promise<BackstageUserIdentity>;
   getCredentials(): Promise<{
@@ -732,14 +728,6 @@ export type SignInPageProps = {
   onSignInSuccess(identityApi: IdentityApi_2): void;
 };
 
-// @public @deprecated
-export type SignInResult = {
-  userId: string;
-  profile: ProfileInfo_2;
-  getIdToken?: () => Promise<string>;
-  signOut?: () => Promise<void>;
-};
-
 // @public
 export interface StorageApi {
   forBucket(name: string): StorageApi;
diff --git a/packages/core-plugin-api/src/apis/definitions/IdentityApi.ts b/packages/core-plugin-api/src/apis/definitions/IdentityApi.ts
index fe4de89106..1b127a1971 100644
--- a/packages/core-plugin-api/src/apis/definitions/IdentityApi.ts
+++ b/packages/core-plugin-api/src/apis/definitions/IdentityApi.ts
@@ -22,31 +22,6 @@ import { BackstageUserIdentity, ProfileInfo } from './auth';
  * @public
  */
 export type IdentityApi = {
-  /**
-   * The ID of the signed in user. This ID is not meant to be presented to the user, but used
-   * as an opaque string to pass on to backends or use in frontend logic.
-   *
-   * @deprecated use {@link IdentityApi.getBackstageIdentity} instead.
-   */
-  getUserId(): string;
-
-  /**
-   * An OpenID Connect ID Token which proves the identity of the signed in user.
-   *
-   * The ID token will be undefined if the signed in user does not have a verified
-   * identity, such as a demo user or mocked user for e2e tests.
-   *
-   * @deprecated use {@link IdentityApi.getCredentials} instead.
-   */
-  getIdToken(): Promise<string | undefined>;
-
-  /**
-   * The profile of the signed in user.
-   *
-   * @deprecated use {@link IdentityApi.getProfileInfo} instead.
-   */
-  getProfile(): ProfileInfo;
-
   /**
    * The profile of the signed in user.
    */
diff --git a/packages/core-plugin-api/src/app/types.ts b/packages/core-plugin-api/src/app/types.ts
index df78728a21..2a71eda1f4 100644
--- a/packages/core-plugin-api/src/app/types.ts
+++ b/packages/core-plugin-api/src/app/types.ts
@@ -20,7 +20,6 @@
 // eslint-disable-next-line no-restricted-imports
 export type {
   BootErrorPageProps,
-  SignInResult,
   SignInPageProps,
   ErrorBoundaryFallbackProps,
   AppComponents,