diff --git a/packages/google-vertex/src/google-vertex-language-model.test.ts b/packages/google-vertex/src/google-vertex-language-model.test.ts
index bb8780bae78..268a001810b 100644
--- a/packages/google-vertex/src/google-vertex-language-model.test.ts
+++ b/packages/google-vertex/src/google-vertex-language-model.test.ts
@@ -153,6 +153,7 @@ describe('doGenerate', () => {
         frequencyPenalty: undefined,
         maxOutputTokens: undefined,
         responseMimeType: undefined,
+        responseSchema: undefined,
         temperature: undefined,
         topK: undefined,
         topP: undefined,
@@ -234,6 +235,7 @@ describe('doGenerate', () => {
       generationConfig: {
         maxOutputTokens: 100,
         responseMimeType: undefined,
+        responseSchema: undefined,
         temperature: 0.5,
         topK: 0.1,
         topP: 0.9,
@@ -267,6 +269,7 @@ describe('doGenerate', () => {
         frequencyPenalty: undefined,
         maxOutputTokens: undefined,
         responseMimeType: undefined,
+        responseSchema: undefined,
         stopSequences: undefined,
         temperature: undefined,
         topK: undefined,
@@ -321,46 +324,102 @@ describe('doGenerate', () => {
     });
   });
 
-  it('should set name & description in object-json mode', async () => {
+  it('should pass specification in object-json mode with structuredOutputs = true (default)', async () => {
     const { model, mockVertexAI } = createModel({
-      modelId: 'test-model',
       generateContent: prepareResponse({
-        parts: [{ text: '{"value":"Spark"}' }],
+        text: '{"property1":"value1","property2":"value2"}',
       }),
     });
 
-    const response = await model.doGenerate({
+    const result = await model.doGenerate({
       inputFormat: 'prompt',
       mode: {
         type: 'object-json',
-        name: 'test-name',
-        description: 'test description',
         schema: {
           type: 'object',
-          properties: { value: { type: 'string' } },
-          required: ['value'],
+          properties: {
+            property1: { type: 'string' },
+            property2: { type: 'number' },
+          },
+          required: ['property1', 'property2'],
+          additionalProperties: false,
+        },
+      },
+      prompt: TEST_PROMPT,
+    });
+
+    expect(mockVertexAI.lastModelParams).toStrictEqual({
+      generationConfig: {
+        frequencyPenalty: undefined,
+        maxOutputTokens: undefined,
+        responseMimeType: 'application/json',
+        responseSchema: {
+          properties: {
+            property1: { type: 'string' },
+            property2: { type: 'number' },
+          },
+          required: ['property1', 'property2'],
+          type: 'object',
+        },
+        stopSequences: undefined,
+        temperature: undefined,
+        topK: undefined,
+        topP: undefined,
+      },
+      model: 'gemini-1.0-pro-002',
+      safetySettings: undefined,
+    });
+
+    expect(result.text).toStrictEqual(
+      '{"property1":"value1","property2":"value2"}',
+    );
+  });
+
+  it('should not pass specification in object-json mode with structuredOutputs = false', async () => {
+    const { model, mockVertexAI } = createModel({
+      generateContent: prepareResponse({
+        text: '{"property1":"value1","property2":"value2"}',
+      }),
+      settings: {
+        structuredOutputs: false,
+      },
+    });
+
+    const result = await model.doGenerate({
+      inputFormat: 'prompt',
+      mode: {
+        type: 'object-json',
+        schema: {
+          type: 'object',
+          properties: {
+            property1: { type: 'string' },
+            property2: { type: 'number' },
+          },
+          required: ['property1', 'property2'],
           additionalProperties: false,
-          $schema: 'http://json-schema.org/draft-07/schema#',
         },
       },
       prompt: TEST_PROMPT,
     });
 
     expect(mockVertexAI.lastModelParams).toStrictEqual({
-      model: 'test-model',
       generationConfig: {
         frequencyPenalty: undefined,
         maxOutputTokens: undefined,
         responseMimeType: 'application/json',
+        responseSchema: undefined,
         stopSequences: undefined,
         temperature: undefined,
         topK: undefined,
         topP: undefined,
       },
+      model: 'gemini-1.0-pro-002',
       safetySettings: undefined,
     });
 
-    expect(response.text).toStrictEqual('{"value":"Spark"}');
+    expect(result.text).toStrictEqual(
+      '{"property1":"value1","property2":"value2"}',
+    );
   });
 
   it('should support object-tool mode', async () => {
@@ -403,6 +462,7 @@ describe('doGenerate', () => {
         frequencyPenalty: undefined,
         maxOutputTokens: undefined,
         responseMimeType: undefined,
+        responseSchema: undefined,
         temperature: undefined,
         topK: undefined,
         topP: undefined,
diff --git a/packages/google-vertex/src/google-vertex-language-model.ts b/packages/google-vertex/src/google-vertex-language-model.ts
index 2879d34e8b5..d9a267d0f5d 100644
--- a/packages/google-vertex/src/google-vertex-language-model.ts
+++ b/packages/google-vertex/src/google-vertex-language-model.ts
@@ -13,6 +13,7 @@ import {
   GenerateContentResponse,
   GenerationConfig,
   Part,
+  ResponseSchema,
   SafetySetting,
   Tool,
   ToolConfig,
@@ -33,9 +34,13 @@ type GoogleVertexAIConfig = {
 export class GoogleVertexLanguageModel implements LanguageModelV1 {
   readonly specificationVersion = 'v1';
   readonly provider = 'google-vertex';
-  readonly defaultObjectGenerationMode = 'tool';
+  readonly defaultObjectGenerationMode = 'json';
   readonly supportsImageUrls = false;
 
+  get supportsObjectGeneration() {
+    return this.settings.structuredOutputs !== false;
+  }
+
   readonly modelId: GoogleVertexModelId;
   readonly settings: GoogleVertexSettings;
 
@@ -98,8 +103,20 @@ export class GoogleVertexLanguageModel implements LanguageModelV1 {
       temperature,
       topP,
       stopSequences,
+
+      // response format:
       responseMimeType:
         responseFormat?.type === 'json' ? 'application/json' : undefined,
+      responseSchema:
+        responseFormat?.type === 'json' &&
+        responseFormat.schema != null &&
+        // Google Vertex does not support all OpenAPI Schema features,
+        // so this is needed as an escape hatch:
+        this.supportsObjectGeneration
+          ? (convertJSONSchemaToOpenAPISchema(
+              responseFormat.schema,
+            ) as ResponseSchema)
+          : undefined,
     };
 
     const type = mode.type;
@@ -132,6 +149,15 @@ export class GoogleVertexLanguageModel implements LanguageModelV1 {
             generationConfig: {
               ...generationConfig,
               responseMimeType: 'application/json',
+              responseSchema:
+                mode.schema != null &&
+                // Google Vertex does not support all OpenAPI Schema features,
+                // so this is needed as an escape hatch:
+                this.supportsObjectGeneration
+                  ? (convertJSONSchemaToOpenAPISchema(
+                      mode.schema,
+                    ) as ResponseSchema)
+                  : undefined,
             },
             safetySettings: this.settings.safetySettings as
               | undefined
diff --git a/packages/google-vertex/src/google-vertex-settings.ts b/packages/google-vertex/src/google-vertex-settings.ts
index 06b0382cd1f..6e76ca5eb3a 100644
--- a/packages/google-vertex/src/google-vertex-settings.ts
+++ b/packages/google-vertex/src/google-vertex-settings.ts
@@ -18,6 +18,16 @@ Models running with nucleus sampling don't allow topK setting.
    */
   topK?: number;
 
+  /**
+   * Optional. Enable structured output. Default is true.
+   *
+   * This is useful when the JSON Schema contains elements that are
+   * not supported by the OpenAPI schema version that
+   * Google Generative AI uses. You can use this to disable
+   * structured outputs if you need to.
+   */
+  structuredOutputs?: boolean;
+
   /**
 Optional. A list of unique safety settings for blocking unsafe content.
    */