diff --git a/packages/keyring-sdk/CHANGELOG.md b/packages/keyring-sdk/CHANGELOG.md
index 82995ff6..d82090d2 100644
--- a/packages/keyring-sdk/CHANGELOG.md
+++ b/packages/keyring-sdk/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Add `encodeMnemonic` ([#495](https://github.com/MetaMask/accounts/pull/495))
+
 ### Changed
 
 - Bump `@metamask/utils` from `^11.1.0` to `^11.10.0` ([#489](https://github.com/MetaMask/accounts/pull/489))
diff --git a/packages/keyring-sdk/package.json b/packages/keyring-sdk/package.json
index 8a3329e8..f324e157 100644
--- a/packages/keyring-sdk/package.json
+++ b/packages/keyring-sdk/package.json
@@ -49,6 +49,7 @@
     "@metamask/eth-sig-util": "^8.2.0",
     "@metamask/keyring-api": "^22.0.0",
     "@metamask/keyring-utils": "^3.2.0",
+    "@metamask/scure-bip39": "^2.1.1",
     "@metamask/superstruct": "^3.1.0",
     "@metamask/utils": "^11.10.0",
     "async-mutex": "^0.5.0",
diff --git a/packages/keyring-sdk/src/index.ts b/packages/keyring-sdk/src/index.ts
index ba41eb93..f942b0d5 100644
--- a/packages/keyring-sdk/src/index.ts
+++ b/packages/keyring-sdk/src/index.ts
@@ -1,3 +1,4 @@
 export * from './keyring-wrapper';
 export * from './keyring-account-registry';
+export * from './mnemonic';
 export * from './eth';
diff --git a/packages/keyring-sdk/src/mnemonic.test.ts b/packages/keyring-sdk/src/mnemonic.test.ts
new file mode 100644
index 00000000..17b39747
--- /dev/null
+++ b/packages/keyring-sdk/src/mnemonic.test.ts
@@ -0,0 +1,34 @@
+import { encodeMnemonic } from './mnemonic';
+
+const toIndicesBytes = (indices: number[]): Uint8Array =>
+  new Uint8Array(new Uint16Array(indices).buffer);
+
+describe('encodeMnemonic', () => {
+  it('returns an empty array for empty input', () => {
+    expect(encodeMnemonic(toIndicesBytes([]))).toStrictEqual([]);
+  });
+
+  it('encodes a single word (index 0 → "abandon")', () => {
+    const expected = Array.from(new TextEncoder().encode('abandon'));
+    expect(encodeMnemonic(toIndicesBytes([0]))).toStrictEqual(expected);
+  });
+
+  it('encodes two words separated by a space', () => {
+    // index 0 → "abandon", index 1 → "ability"
+    const expected = Array.from(new TextEncoder().encode('abandon ability'));
+    expect(encodeMnemonic(toIndicesBytes([0, 1]))).toStrictEqual(expected);
+  });
+
+  it('encodes a standard 12-word mnemonic (all "abandon")', () => {
+    const indices = new Array(12).fill(0);
+    const expected = Array.from(
+      new TextEncoder().encode(new Array(12).fill('abandon').join(' ')),
+    );
+    expect(encodeMnemonic(toIndicesBytes(indices))).toStrictEqual(expected);
+  });
+
+  it('returns number[] (not a Uint8Array)', () => {
+    const result = encodeMnemonic(toIndicesBytes([0]));
+    expect(Array.isArray(result)).toBe(true);
+  });
+});
diff --git a/packages/keyring-sdk/src/mnemonic.ts b/packages/keyring-sdk/src/mnemonic.ts
new file mode 100644
index 00000000..524e5d2c
--- /dev/null
+++ b/packages/keyring-sdk/src/mnemonic.ts
@@ -0,0 +1,18 @@
+import { wordlist } from '@metamask/scure-bip39/dist/wordlists/english';
+
+/**
+ * Encodes a mnemonic as an array of bytes (UTF-8).
+ *
+ * @param mnemonicIndicesBytes - An array of bytes (16-bit unsigned integers) representing the indices of the words in the mnemonic.
+ * @returns An array of bytes (UTF-8) representing the mnemonic.
+ */
+export function encodeMnemonic(mnemonicIndicesBytes: Uint8Array): number[] {
+  const mnemonicIndices = Array.from(
+    // Create a new `Uint8Array` to ensure we have a proper view on the buffer
+    // without having to worry about `byteOffset` and `byteLength` of
+    // the inner buffer.
+    new Uint16Array(new Uint8Array(mnemonicIndicesBytes).buffer),
+  );
+  const mnemonic = mnemonicIndices.map((i) => wordlist[i]).join(' ');
+  return Array.from(new TextEncoder().encode(mnemonic));
+}
diff --git a/yarn.lock b/yarn.lock
index a1ba37be..13fdd6d7 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2126,6 +2126,7 @@ __metadata:
     "@metamask/eth-sig-util": "npm:^8.2.0"
     "@metamask/keyring-api": "npm:^22.0.0"
     "@metamask/keyring-utils": "npm:^3.2.0"
+    "@metamask/scure-bip39": "npm:^2.1.1"
     "@metamask/superstruct": "npm:^3.1.0"
     "@metamask/utils": "npm:^11.10.0"
     "@ts-bridge/cli": "npm:^0.6.3"