diff --git a/.changeset/funny-baboons-yell.md b/.changeset/funny-baboons-yell.md
new file mode 100644
index 00000000000..3069e121a8c
--- /dev/null
+++ b/.changeset/funny-baboons-yell.md
@@ -0,0 +1,5 @@
+---
+'@firebase/vertexai': patch
+---
+
+Add `HarmSeverity.HARM_SEVERITY_UNSPECIFIED`.
diff --git a/common/api-review/vertexai.api.md b/common/api-review/vertexai.api.md
index c0b28466bd7..a8287c34549 100644
--- a/common/api-review/vertexai.api.md
+++ b/common/api-review/vertexai.api.md
@@ -410,7 +410,8 @@ export enum HarmSeverity {
     HARM_SEVERITY_HIGH = "HARM_SEVERITY_HIGH",
     HARM_SEVERITY_LOW = "HARM_SEVERITY_LOW",
     HARM_SEVERITY_MEDIUM = "HARM_SEVERITY_MEDIUM",
-    HARM_SEVERITY_NEGLIGIBLE = "HARM_SEVERITY_NEGLIGIBLE"
+    HARM_SEVERITY_NEGLIGIBLE = "HARM_SEVERITY_NEGLIGIBLE",
+    HARM_SEVERITY_UNSPECIFIED = "HARM_SEVERITY_UNSPECIFIED"
 }
 
 // @beta
diff --git a/docs-devsite/vertexai.md b/docs-devsite/vertexai.md
index eb805c7710f..ef0dc0d1947 100644
--- a/docs-devsite/vertexai.md
+++ b/docs-devsite/vertexai.md
@@ -414,6 +414,7 @@ export declare enum HarmSeverity
 |  HARM\_SEVERITY\_LOW | <code>&quot;HARM_SEVERITY_LOW&quot;</code> | Low level of harm severity. |
 |  HARM\_SEVERITY\_MEDIUM | <code>&quot;HARM_SEVERITY_MEDIUM&quot;</code> | Medium level of harm severity. |
 |  HARM\_SEVERITY\_NEGLIGIBLE | <code>&quot;HARM_SEVERITY_NEGLIGIBLE&quot;</code> | Negligible level of harm severity. |
+|  HARM\_SEVERITY\_UNSPECIFIED | <code>&quot;HARM_SEVERITY_UNSPECIFIED&quot;</code> | Unspecified level of harm severity. |
 
 ## ImagenAspectRatio
 
diff --git a/packages/vertexai/src/types/enums.ts b/packages/vertexai/src/types/enums.ts
index a9481d40f5f..1ff6a1abac3 100644
--- a/packages/vertexai/src/types/enums.ts
+++ b/packages/vertexai/src/types/enums.ts
@@ -103,6 +103,10 @@ export enum HarmProbability {
  * @public
  */
 export enum HarmSeverity {
+  /**
+   * Unspecified level of harm severity.
+   */
+  HARM_SEVERITY_UNSPECIFIED = 'HARM_SEVERITY_UNSPECIFIED',
   /**
    * Negligible level of harm severity.
    */