diff --git a/packages/controller-utils/src/util.test.ts b/packages/controller-utils/src/util.test.ts
index bbf993af5cc..26e90b9da51 100644
--- a/packages/controller-utils/src/util.test.ts
+++ b/packages/controller-utils/src/util.test.ts
@@ -277,13 +277,33 @@ describe('util', () => {
   });
 
   describe('toChecksumHexAddress', () => {
-    const fullAddress = `0x${VALID}`;
-    it('should return address for valid address', () => {
-      expect(util.toChecksumHexAddress(fullAddress)).toBe(fullAddress);
+    it('should return an 0x-prefixed checksum address untouched', () => {
+      const address = '0x4e1fF7229BDdAf0A73DF183a88d9c3a04cc975e0';
+      expect(util.toChecksumHexAddress(address)).toBe(address);
     });
 
-    it('should return address for non prefix address', () => {
-      expect(util.toChecksumHexAddress(VALID)).toBe(fullAddress);
+    it('should prefix a non-0x-prefixed checksum address with 0x', () => {
+      expect(
+        util.toChecksumHexAddress('4e1fF7229BDdAf0A73DF183a88d9c3a04cc975e0'),
+      ).toBe('0x4e1fF7229BDdAf0A73DF183a88d9c3a04cc975e0');
+    });
+
+    it('should convert a non-checksum address to a checksum address', () => {
+      expect(
+        util.toChecksumHexAddress('0x4e1ff7229bddaf0a73df183a88d9c3a04cc975e0'),
+      ).toBe('0x4e1fF7229BDdAf0A73DF183a88d9c3a04cc975e0');
+    });
+
+    it('should return "0x" if given an empty string', () => {
+      expect(util.toChecksumHexAddress('')).toBe('0x');
+    });
+
+    it('should return the input untouched if it is undefined', () => {
+      expect(util.toChecksumHexAddress(undefined)).toBeUndefined();
+    });
+
+    it('should return the input untouched if it is null', () => {
+      expect(util.toChecksumHexAddress(null)).toBeNull();
     });
   });
 
diff --git a/packages/controller-utils/src/util.ts b/packages/controller-utils/src/util.ts
index ed2503cd087..c9bf11c9b2a 100644
--- a/packages/controller-utils/src/util.ts
+++ b/packages/controller-utils/src/util.ts
@@ -251,20 +251,45 @@ export async function safelyExecuteWithTimeout<Result>(
 }
 
 /**
- * Convert an address to a checksummed hexidecimal address.
+ * Convert an address to a checksummed hexadecimal address.
  *
  * @param address - The address to convert.
- * @returns A 0x-prefixed hexidecimal checksummed address, if address is valid. Otherwise original input 0x-prefixe, if address is valid. Otherwise original input 0x-prefixed.
+ * @returns The address in 0x-prefixed hexadecimal checksummed form if it is valid.
  */
-export function toChecksumHexAddress(address: string) {
+export function toChecksumHexAddress(address: string): string;
+
+/**
+ * Convert an address to a checksummed hexadecimal address.
+ *
+ * Note that this particular overload does nothing.
+ *
+ * @param address - A value that is not a string (e.g. `undefined` or `null`).
+ * @returns The `address` untouched.
+ * @deprecated This overload is designed to gracefully handle an invalid input
+ * and is only present for backward compatibility. It may be removed in a future
+ * major version. Please pass a string to `toChecksumHexAddress` instead.
+ */
+export function toChecksumHexAddress<T>(address: T): T;
+
+// Tools only see JSDocs for overloads and ignore them for the implementation.
+// eslint-disable-next-line jsdoc/require-jsdoc
+export function toChecksumHexAddress(address: unknown) {
+  if (typeof address !== 'string') {
+    // Mimic behavior of `addHexPrefix` from `ethereumjs-util` (which this
+    // function was previously using) for backward compatibility.
+    return address;
+  }
+
   const hexPrefixed = add0x(address);
+
   if (!isHexString(hexPrefixed)) {
-    // Version 5.1 of ethereumjs-utils would have returned '0xY' for input 'y'
+    // Version 5.1 of ethereumjs-util would have returned '0xY' for input 'y'
     // but we shouldn't waste effort trying to change case on a clearly invalid
     // string. Instead just return the hex prefixed original string which most
     // closely mimics the original behavior.
     return hexPrefixed;
   }
+
   return toChecksumAddress(hexPrefixed);
 }
 
diff --git a/packages/preferences-controller/src/PreferencesController.ts b/packages/preferences-controller/src/PreferencesController.ts
index 2bf761950a4..b7451b2c27f 100644
--- a/packages/preferences-controller/src/PreferencesController.ts
+++ b/packages/preferences-controller/src/PreferencesController.ts
@@ -254,7 +254,9 @@ export class PreferencesController extends BaseController<
    * @param addresses - List of addresses to use to generate new identities.
    */
   addIdentities(addresses: string[]) {
-    const checksummedAddresses = addresses.map(toChecksumHexAddress);
+    const checksummedAddresses = addresses.map((address) =>
+      toChecksumHexAddress(address),
+    );
     this.update((state) => {
       const { identities } = state;
       for (const address of checksummedAddresses) {