diff --git a/app/scripts/controller-init/messengers/index.ts b/app/scripts/controller-init/messengers/index.ts
index a00540f4aa15..faf15fea021b 100644
--- a/app/scripts/controller-init/messengers/index.ts
+++ b/app/scripts/controller-init/messengers/index.ts
@@ -1,3 +1,4 @@
+import { noop } from 'lodash';
 import {
   getPPOMControllerMessenger,
   getPPOMControllerInitMessenger,
@@ -26,18 +27,23 @@ import {
 export const CONTROLLER_MESSENGERS = {
   CronjobController: {
     getMessenger: getCronjobControllerMessenger,
+    getInitMessenger: noop,
   },
   ExecutionService: {
     getMessenger: getExecutionServiceMessenger,
+    getInitMessenger: noop,
   },
   MultichainAssetsController: {
     getMessenger: getMultichainAssetsControllerMessenger,
+    getInitMessenger: noop,
   },
   MultichainBalancesController: {
     getMessenger: getMultichainBalancesControllerMessenger,
+    getInitMessenger: noop,
   },
   MultichainTransactionsController: {
     getMessenger: getMultichainTransactionsControllerMessenger,
+    getInitMessenger: noop,
   },
   RateLimitController: {
     getMessenger: getRateLimitControllerMessenger,
@@ -45,6 +51,7 @@ export const CONTROLLER_MESSENGERS = {
   },
   SnapsRegistry: {
     getMessenger: getSnapsRegistryMessenger,
+    getInitMessenger: noop,
   },
   SnapController: {
     getMessenger: getSnapControllerMessenger,
@@ -52,9 +59,11 @@ export const CONTROLLER_MESSENGERS = {
   },
   SnapInsightsController: {
     getMessenger: getSnapInsightsControllerMessenger,
+    getInitMessenger: noop,
   },
   SnapInterfaceController: {
     getMessenger: getSnapInterfaceControllerMessenger,
+    getInitMessenger: noop,
   },
   PPOMController: {
     getMessenger: getPPOMControllerMessenger,
diff --git a/app/scripts/controller-init/multichain/multichain-assets-controller-init.test.ts b/app/scripts/controller-init/multichain/multichain-assets-controller-init.test.ts
index fa2f8e470e6a..0763242da197 100644
--- a/app/scripts/controller-init/multichain/multichain-assets-controller-init.test.ts
+++ b/app/scripts/controller-init/multichain/multichain-assets-controller-init.test.ts
@@ -20,6 +20,7 @@ function buildInitRequestMock(): jest.Mocked<
     controllerMessenger: getMultichainAssetsControllerMessenger(
       baseControllerMessenger,
     ),
+    initMessenger: undefined,
   };
 }
 
diff --git a/app/scripts/controller-init/multichain/multichain-balances-controller-init.test.ts b/app/scripts/controller-init/multichain/multichain-balances-controller-init.test.ts
index 453aa81092a0..c51e9e1e454f 100644
--- a/app/scripts/controller-init/multichain/multichain-balances-controller-init.test.ts
+++ b/app/scripts/controller-init/multichain/multichain-balances-controller-init.test.ts
@@ -20,6 +20,7 @@ function buildInitRequestMock(): jest.Mocked<
     controllerMessenger: getMultichainBalancesControllerMessenger(
       baseControllerMessenger,
     ),
+    initMessenger: undefined,
   };
 }
 
diff --git a/app/scripts/controller-init/multichain/multichain-transactions-controller-init.test.ts b/app/scripts/controller-init/multichain/multichain-transactions-controller-init.test.ts
index ca41b5b177a5..f611b17e4ebf 100644
--- a/app/scripts/controller-init/multichain/multichain-transactions-controller-init.test.ts
+++ b/app/scripts/controller-init/multichain/multichain-transactions-controller-init.test.ts
@@ -20,6 +20,7 @@ function buildInitRequestMock(): jest.Mocked<
     controllerMessenger: getMultichainTransactionsControllerMessenger(
       baseControllerMessenger,
     ),
+    initMessenger: undefined,
   };
 }
 
diff --git a/app/scripts/controller-init/snaps/cronjob-controller-init.test.ts b/app/scripts/controller-init/snaps/cronjob-controller-init.test.ts
index 932a956f8d8a..f31e28747af4 100644
--- a/app/scripts/controller-init/snaps/cronjob-controller-init.test.ts
+++ b/app/scripts/controller-init/snaps/cronjob-controller-init.test.ts
@@ -21,6 +21,7 @@ function getInitRequestMock(): jest.Mocked<
   const requestMock = {
     ...buildControllerInitRequestMock(),
     controllerMessenger: getCronjobControllerMessenger(baseMessenger),
+    initMessenger: undefined,
   };
 
   return requestMock;
diff --git a/app/scripts/controller-init/snaps/execution-service-init.test.ts b/app/scripts/controller-init/snaps/execution-service-init.test.ts
index d5b877201e40..033baedd321a 100644
--- a/app/scripts/controller-init/snaps/execution-service-init.test.ts
+++ b/app/scripts/controller-init/snaps/execution-service-init.test.ts
@@ -24,6 +24,7 @@ function getInitRequestMock(): jest.Mocked<
   const requestMock = {
     ...buildControllerInitRequestMock(),
     controllerMessenger: getExecutionServiceMessenger(baseMessenger),
+    initMessenger: undefined,
   };
 
   return requestMock;
diff --git a/app/scripts/controller-init/snaps/snap-insights-controller-init.test.ts b/app/scripts/controller-init/snaps/snap-insights-controller-init.test.ts
index bd83b4abc794..e0db4f98e0f5 100644
--- a/app/scripts/controller-init/snaps/snap-insights-controller-init.test.ts
+++ b/app/scripts/controller-init/snaps/snap-insights-controller-init.test.ts
@@ -18,6 +18,7 @@ function getInitRequestMock(): jest.Mocked<
   const requestMock = {
     ...buildControllerInitRequestMock(),
     controllerMessenger: getSnapInsightsControllerMessenger(baseMessenger),
+    initMessenger: undefined,
   };
 
   return requestMock;
diff --git a/app/scripts/controller-init/snaps/snap-interface-controller-init.test.ts b/app/scripts/controller-init/snaps/snap-interface-controller-init.test.ts
index 2101ed1c706b..588c7eb7bac1 100644
--- a/app/scripts/controller-init/snaps/snap-interface-controller-init.test.ts
+++ b/app/scripts/controller-init/snaps/snap-interface-controller-init.test.ts
@@ -18,6 +18,7 @@ function getInitRequestMock(): jest.Mocked<
   const requestMock = {
     ...buildControllerInitRequestMock(),
     controllerMessenger: getSnapInterfaceControllerMessenger(baseMessenger),
+    initMessenger: undefined,
   };
 
   return requestMock;
diff --git a/app/scripts/controller-init/snaps/snaps-registry-init.test.ts b/app/scripts/controller-init/snaps/snaps-registry-init.test.ts
index e26d51a7f588..46e33068442f 100644
--- a/app/scripts/controller-init/snaps/snaps-registry-init.test.ts
+++ b/app/scripts/controller-init/snaps/snaps-registry-init.test.ts
@@ -18,6 +18,7 @@ function getInitRequestMock(): jest.Mocked<
   const requestMock = {
     ...buildControllerInitRequestMock(),
     controllerMessenger: getSnapsRegistryMessenger(baseMessenger),
+    initMessenger: undefined,
   };
 
   return requestMock;
diff --git a/app/scripts/controller-init/types.ts b/app/scripts/controller-init/types.ts
index 1f16af803bc4..9af50172feea 100644
--- a/app/scripts/controller-init/types.ts
+++ b/app/scripts/controller-init/types.ts
@@ -161,15 +161,13 @@ export type ControllerInitRequest<
     message: string,
     url?: string,
   ) => Promise<void>;
-} & (InitMessengerType extends BaseRestrictedControllerMessenger
-  ? {
-      /**
-       * Required initialization messenger instance.
-       * Generated using the callback specified in `getInitMessengerCallback`.
-       */
-      initMessenger: InitMessengerType;
-    }
-  : unknown);
+
+  /**
+   * Required initialization messenger instance.
+   * Generated using the callback specified in `getInitMessengerCallback`.
+   */
+  initMessenger: InitMessengerType;
+};
 
 /**
  * A single background API method available to the UI.
diff --git a/app/scripts/controller-init/utils.ts b/app/scripts/controller-init/utils.ts
index 2bbaf7abf4ea..b9eba4498651 100644
--- a/app/scripts/controller-init/utils.ts
+++ b/app/scripts/controller-init/utils.ts
@@ -29,14 +29,26 @@ export type InitControllersResult = {
 
 type BaseControllerInitRequest = ControllerInitRequest<
   BaseRestrictedControllerMessenger,
-  BaseRestrictedControllerMessenger
+  BaseRestrictedControllerMessenger | void
 >;
 
 type ControllerMessengerCallback = (
   BaseControllerMessenger: BaseControllerMessenger,
 ) => BaseRestrictedControllerMessenger;
 
-type ControllersToInitialize = 'PPOMController' | 'TransactionController';
+export type ControllersToInitialize =
+  | 'CronjobController'
+  | 'ExecutionService'
+  | 'MultichainAssetsController'
+  | 'MultichainBalancesController'
+  | 'MultichainTransactionsController'
+  | 'RateLimitController'
+  | 'SnapsRegistry'
+  | 'SnapController'
+  | 'SnapInsightsController'
+  | 'SnapInterfaceController'
+  | 'PPOMController'
+  | 'TransactionController';
 
 type InitFunction<Name extends ControllersToInitialize> =
   ControllerInitFunction<
@@ -101,7 +113,6 @@ export function initControllers({
     const messengerCallbacks = CONTROLLER_MESSENGERS[controllerName];
 
     const controllerMessengerCallback =
-      // @ts-expect-error TODO: Resolve mismatch between base-controller versions.
       messengerCallbacks?.getMessenger as ControllerMessengerCallback;
 
     const initMessengerCallback =
@@ -120,11 +131,8 @@ export function initControllers({
       initMessenger,
     };
 
-    // TODO: Remove @ts-expect-error once base-controller version mismatch is resolved
-    // Instead of suppressing all type errors, we'll be specific about the controllerMessenger mismatch
     const result = initFunction({
       ...finalInitRequest,
-      // @ts-expect-error TODO: Resolve mismatch between base-controller versions.
       controllerMessenger: finalInitRequest.controllerMessenger,
     });
 
@@ -144,8 +152,8 @@ export function initControllers({
     const memStateKey =
       memStateKeyRaw === null ? undefined : memStateKeyRaw ?? controllerName;
 
-    partialControllersByName[controllerName] = controller as Controller &
-      undefined;
+    // @ts-expect-error: Union too complex.
+    partialControllersByName[controllerName] = controller;
 
     controllerApi = {
       ...controllerApi,