diff --git a/dev-packages/node-integration-tests/suites/tracing/openai/scenario-message-truncation.mjs b/dev-packages/node-integration-tests/suites/tracing/openai/scenario-message-truncation-completions.mjs
similarity index 97%
rename from dev-packages/node-integration-tests/suites/tracing/openai/scenario-message-truncation.mjs
rename to dev-packages/node-integration-tests/suites/tracing/openai/scenario-message-truncation-completions.mjs
index 5623d3763657..96684ed9ec4f 100644
--- a/dev-packages/node-integration-tests/suites/tracing/openai/scenario-message-truncation.mjs
+++ b/dev-packages/node-integration-tests/suites/tracing/openai/scenario-message-truncation-completions.mjs
@@ -12,7 +12,7 @@ class MockOpenAI {
           await new Promise(resolve => setTimeout(resolve, 10));
 
           return {
-            id: 'chatcmpl-truncation-test',
+            id: 'chatcmpl-completions-truncation-test',
             object: 'chat.completion',
             created: 1677652288,
             model: params.model,
diff --git a/dev-packages/node-integration-tests/suites/tracing/openai/scenario-message-truncation-responses.mjs b/dev-packages/node-integration-tests/suites/tracing/openai/scenario-message-truncation-responses.mjs
new file mode 100644
index 000000000000..aebd3341eb33
--- /dev/null
+++ b/dev-packages/node-integration-tests/suites/tracing/openai/scenario-message-truncation-responses.mjs
@@ -0,0 +1,93 @@
+import { instrumentOpenAiClient } from '@sentry/core';
+import * as Sentry from '@sentry/node';
+
+class MockOpenAI {
+  constructor(config) {
+    this.apiKey = config.apiKey;
+
+    this.responses = {
+      create: async params => {
+        // Simulate processing time
+        await new Promise(resolve => setTimeout(resolve, 10));
+
+        return {
+          id: 'chatcmpl-responses-truncation-test',
+          object: 'response',
+          created_at: 1677652288,
+          status: 'completed',
+          error: null,
+          incomplete_details: null,
+          instructions: null,
+          max_output_tokens: null,
+          model: params.model,
+          output: [
+            {
+              type: 'message',
+              id: 'message-123',
+              status: 'completed',
+              role: 'assistant',
+              content: [
+                {
+                  type: 'output_text',
+                  text: 'Response to truncated messages',
+                  annotations: [],
+                },
+              ],
+            },
+          ],
+          parallel_tool_calls: true,
+          previous_response_id: null,
+          reasoning: {
+            effort: null,
+            summary: null,
+          },
+          store: true,
+          temperature: params.temperature,
+          text: {
+            format: {
+              type: 'text',
+            },
+          },
+          tool_choice: 'auto',
+          tools: [],
+          top_p: 1.0,
+          truncation: 'disabled',
+          usage: {
+            input_tokens: 10,
+            input_tokens_details: {
+              cached_tokens: 0,
+            },
+            output_tokens: 15,
+            output_tokens_details: {
+              reasoning_tokens: 0,
+            },
+            total_tokens: 25,
+          },
+          user: null,
+          metadata: {},
+        };
+      },
+    };
+  }
+}
+
+async function run() {
+  await Sentry.startSpan({ op: 'function', name: 'main' }, async () => {
+    const mockClient = new MockOpenAI({
+      apiKey: 'mock-api-key',
+    });
+
+    const client = instrumentOpenAiClient(mockClient);
+
+    // Create 1 large message that gets truncated to fit within the 20KB limit
+    const largeContent = 'A'.repeat(25000) + 'B'.repeat(25000); // ~50KB gets truncated to include only As
+
+    await client.responses.create({
+      model: 'gpt-3.5-turbo',
+      input: largeContent,
+      temperature: 0.7,
+    });
+  });
+}
+
+run();
diff --git a/dev-packages/node-integration-tests/suites/tracing/openai/test.ts b/dev-packages/node-integration-tests/suites/tracing/openai/test.ts
index 218e3c7ee61f..5cbb27df73bf 100644
--- a/dev-packages/node-integration-tests/suites/tracing/openai/test.ts
+++ b/dev-packages/node-integration-tests/suites/tracing/openai/test.ts
@@ -400,7 +400,7 @@ describe('OpenAI integration', () => {
 
   createEsmAndCjsTests(
     __dirname,
-    'scenario-message-truncation.mjs',
+    'scenario-message-truncation-completions.mjs',
     'instrument-with-pii.mjs',
     (createRunner, test) => {
       test('truncates messages when they exceed byte limit - keeps only last message and crops it', async () => {
@@ -433,4 +433,40 @@ describe('OpenAI integration', () => {
       });
     },
   );
+
+  createEsmAndCjsTests(
+    __dirname,
+    'scenario-message-truncation-responses.mjs',
+    'instrument-with-pii.mjs',
+    (createRunner, test) => {
+      test('truncates string inputs when they exceed byte limit', async () => {
+        await createRunner()
+          .ignore('event')
+          .expect({
+            transaction: {
+              transaction: 'main',
+              spans: expect.arrayContaining([
+                expect.objectContaining({
+                  data: expect.objectContaining({
+                    'gen_ai.operation.name': 'responses',
+                    'sentry.op': 'gen_ai.responses',
+                    'sentry.origin': 'auto.ai.openai',
+                    'gen_ai.system': 'openai',
+                    'gen_ai.request.model': 'gpt-3.5-turbo',
+                    // Messages should be present and should include truncated string input (contains only As)
+                    'gen_ai.request.messages': expect.stringMatching(/^A+$/),
+                  }),
+                  description: 'responses gpt-3.5-turbo',
+                  op: 'gen_ai.responses',
+                  origin: 'auto.ai.openai',
+                  status: 'ok',
+                }),
+              ]),
+            },
+          })
+          .start()
+          .completed();
+      });
+    },
+  );
 });
diff --git a/packages/core/src/utils/ai/messageTruncation.ts b/packages/core/src/utils/ai/messageTruncation.ts
index 64d186f927b8..945761f6220c 100644
--- a/packages/core/src/utils/ai/messageTruncation.ts
+++ b/packages/core/src/utils/ai/messageTruncation.ts
@@ -294,3 +294,13 @@ export function truncateMessagesByBytes(messages: unknown[], maxBytes: number):
 export function truncateGenAiMessages(messages: unknown[]): unknown[] {
   return truncateMessagesByBytes(messages, DEFAULT_GEN_AI_MESSAGES_BYTE_LIMIT);
 }
+
+/**
+ * Truncate GenAI string input using the default byte limit.
+ *
+ * @param input - The string to truncate
+ * @returns Truncated string
+ */
+export function truncateGenAiStringInput(input: string): string {
+  return truncateTextByBytes(input, DEFAULT_GEN_AI_MESSAGES_BYTE_LIMIT);
+}
diff --git a/packages/core/src/utils/ai/utils.ts b/packages/core/src/utils/ai/utils.ts
index 00e147a16e5f..4a7a14eea554 100644
--- a/packages/core/src/utils/ai/utils.ts
+++ b/packages/core/src/utils/ai/utils.ts
@@ -7,7 +7,7 @@ import {
   GEN_AI_USAGE_OUTPUT_TOKENS_ATTRIBUTE,
   GEN_AI_USAGE_TOTAL_TOKENS_ATTRIBUTE,
 } from './gen-ai-attributes';
-import { truncateGenAiMessages } from './messageTruncation';
+import { truncateGenAiMessages, truncateGenAiStringInput } from './messageTruncation';
 /**
  * Maps AI method paths to Sentry operation name
  */
@@ -95,7 +95,7 @@ export function setTokenUsageAttributes(
 export function getTruncatedJsonString<T>(value: T | T[]): string {
   if (typeof value === 'string') {
     // Some values are already JSON strings, so we don't need to duplicate the JSON parsing
-    return value;
+    return truncateGenAiStringInput(value);
   }
   if (Array.isArray(value)) {
     // truncateGenAiMessages returns an array of strings, so we need to stringify it