diff --git a/.changeset/m2m-token-timestamp-units.md b/.changeset/m2m-token-timestamp-units.md
new file mode 100644
index 00000000000..fc12e04daf7
--- /dev/null
+++ b/.changeset/m2m-token-timestamp-units.md
@@ -0,0 +1,5 @@
+---
+'@clerk/backend': patch
+---
+
+Clarify in the `M2MToken`, `APIKey`, and `IdPOAuthAccessToken` JSDoc that the timestamp properties (`expiration`, `lastUsedAt`, `createdAt`, and `updatedAt`) are Unix timestamps in milliseconds (not seconds).
diff --git a/packages/backend/src/api/resources/APIKey.ts b/packages/backend/src/api/resources/APIKey.ts
index 09f67479b26..38838700aef 100644
--- a/packages/backend/src/api/resources/APIKey.ts
+++ b/packages/backend/src/api/resources/APIKey.ts
@@ -23,17 +23,17 @@ export class APIKey {
     readonly revocationReason: string | null,
     /** Whether the API key has expired. */
     readonly expired: boolean,
-    /** The Unix timestamp when the API key expires. `null` if the API key never expires. */
+    /** The Unix timestamp (in milliseconds) when the API key expires. `null` if the API key never expires. */
     readonly expiration: number | null,
     /** The user ID for the user creating the API key. */
     readonly createdBy: string | null,
     /** A description for the API key. */
     readonly description: string | null,
-    /** The Unix timestamp when the API key was last used to authenticate a request. */
+    /** The Unix timestamp (in milliseconds) when the API key was last used to authenticate a request. */
     readonly lastUsedAt: number | null,
-    /** The Unix timestamp when the API key was created. */
+    /** The Unix timestamp (in milliseconds) when the API key was created. */
     readonly createdAt: number,
-    /** The Unix timestamp when the API key was last updated. */
+    /** The Unix timestamp (in milliseconds) when the API key was last updated. */
     readonly updatedAt: number,
     /** The API key secret. */
     readonly secret?: string,
diff --git a/packages/backend/src/api/resources/IdPOAuthAccessToken.ts b/packages/backend/src/api/resources/IdPOAuthAccessToken.ts
index 41e0d765c70..8399057e59b 100644
--- a/packages/backend/src/api/resources/IdPOAuthAccessToken.ts
+++ b/packages/backend/src/api/resources/IdPOAuthAccessToken.ts
@@ -19,8 +19,11 @@ export class IdPOAuthAccessToken {
     readonly revoked: boolean,
     readonly revocationReason: string | null,
     readonly expired: boolean,
+    /** The Unix timestamp (in milliseconds) when the access token expires. */
     readonly expiration: number | null,
+    /** The Unix timestamp (in milliseconds) when the access token was created. */
     readonly createdAt: number,
+    /** The Unix timestamp (in milliseconds) when the access token was last updated. */
     readonly updatedAt: number,
   ) {}
 
diff --git a/packages/backend/src/api/resources/M2MToken.ts b/packages/backend/src/api/resources/M2MToken.ts
index 95ec6c41b81..5b19fdd9603 100644
--- a/packages/backend/src/api/resources/M2MToken.ts
+++ b/packages/backend/src/api/resources/M2MToken.ts
@@ -55,11 +55,11 @@ export class M2MToken {
     readonly revocationReason: string | null,
     /** Whether the M2M token has expired. */
     readonly expired: boolean,
-    /** The Unix timestamp when the M2M token expires. */
+    /** The Unix timestamp (in milliseconds) when the M2M token expires. */
     readonly expiration: number | null,
-    /** The Unix timestamp when the M2M token was created. */
+    /** The Unix timestamp (in milliseconds) when the M2M token was created. */
     readonly createdAt: number,
-    /** The Unix timestamp when the M2M token was last updated. */
+    /** The Unix timestamp (in milliseconds) when the M2M token was last updated. */
     readonly updatedAt: number,
     /** The token string. */
     readonly token?: string,