diff --git a/x-pack/plugins/observability_ai_assistant/public/components/chat/chat_body.test.tsx b/x-pack/plugins/observability_ai_assistant/public/components/chat/chat_body.test.tsx
new file mode 100644
index 0000000000000..23e1e61e16dc7
--- /dev/null
+++ b/x-pack/plugins/observability_ai_assistant/public/components/chat/chat_body.test.tsx
@@ -0,0 +1,148 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { type Message } from '../../../common/types';
+import { reverseToLastUserMessage } from './chat_body';
+
+describe('<ChatBody>', () => {
+  describe('reverseToLastUserMessage', () => {
+    const firstUserMessage = {
+      message: {
+        role: 'user',
+        content: 'Give me a list of my APM services',
+      },
+    };
+    const firstUserMessageIndex = 1;
+
+    const secondUserMessage = {
+      message: {
+        role: 'user',
+        content: 'Can you tell me about the synth-go-0 service',
+      },
+    };
+    const secondUserMessageIndex = 7;
+
+    const messages = [
+      {
+        message: {
+          role: 'system',
+          content: "You're the best around",
+        },
+      },
+      firstUserMessage,
+      {
+        message: {
+          role: 'assistant',
+          function_call: {
+            name: 'recall',
+            arguments: '{"queries":[],"contexts":[]}',
+            trigger: 'assistant',
+          },
+          content: '',
+        },
+      },
+      {
+        message: {
+          role: 'user',
+          name: 'recall',
+          content: '[]',
+        },
+      },
+      {
+        message: {
+          role: 'assistant',
+          function_call: {
+            name: 'get_apm_services_list',
+            arguments: '{\n  "start": "now-1h",\n  "end": "now"\n}',
+            trigger: 'assistant',
+          },
+          content: '',
+        },
+      },
+      {
+        message: {
+          role: 'user',
+          name: 'get_apm_services_list',
+          content: '[{"service.name":"synth-go-0"}]',
+        },
+      },
+      {
+        message: {
+          role: 'assistant',
+          function_call: {
+            name: '',
+            arguments: '',
+            trigger: 'assistant',
+          },
+          content: 'Here is a list of your APM services:\n\n1. synth-go-0\n',
+        },
+      },
+      secondUserMessage,
+      {
+        message: {
+          role: 'assistant',
+          function_call: {
+            name: 'recall',
+            arguments: '{"queries":[],"contexts":[]}',
+            trigger: 'assistant',
+          },
+          content: '',
+        },
+      },
+      {
+        message: {
+          role: 'user',
+          name: 'recall',
+          content: '[]',
+        },
+      },
+      {
+        message: {
+          role: 'assistant',
+          function_call: {
+            name: 'get_apm_service_summary',
+            arguments:
+              '{\n  "service.name": "synth-go-0",\n  "start": "now-1h",\n  "end": "now"\n}',
+            trigger: 'assistant',
+          },
+          content: '',
+        },
+      },
+      {
+        message: {
+          role: 'user',
+          name: 'get_apm_service_summary',
+          content: '{"service.name":"synth-go-0"}',
+        },
+      },
+      {
+        message: {
+          role: 'assistant',
+          function_call: {
+            name: '',
+            arguments: '',
+            trigger: 'assistant',
+          },
+          content: 'The service named "synth-go-0" is really neat.',
+        },
+      },
+    ] as unknown as Message[];
+
+    it('goes back to the last written user message when regenerating from the end of the conversation', () => {
+      const nextMessages = reverseToLastUserMessage(messages, messages.at(-1)!);
+      expect(nextMessages).toEqual(messages.slice(0, secondUserMessageIndex + 1));
+    });
+
+    it('goes back to the last written user message when regenerating from the middle of the conversation', () => {
+      const nextMessages = reverseToLastUserMessage(
+        messages,
+        messages.at(secondUserMessageIndex - 1)!
+      );
+      expect(nextMessages).toEqual(messages.slice(0, firstUserMessageIndex + 1));
+    });
+  });
+});
diff --git a/x-pack/plugins/observability_ai_assistant/public/components/chat/chat_body.tsx b/x-pack/plugins/observability_ai_assistant/public/components/chat/chat_body.tsx
index 5b7e6b509e69f..15cd44119ce28 100644
--- a/x-pack/plugins/observability_ai_assistant/public/components/chat/chat_body.tsx
+++ b/x-pack/plugins/observability_ai_assistant/public/components/chat/chat_body.tsx
@@ -20,6 +20,7 @@ import {
 import type { AuthenticatedUser } from '@kbn/security-plugin/common';
 import { euiThemeVars } from '@kbn/ui-theme';
 import { i18n } from '@kbn/i18n';
+import { findLastIndex } from 'lodash';
 import { ChatState } from '../../hooks/use_chat';
 import { useConversation } from '../../hooks/use_conversation';
 import { useLicense } from '../../hooks/use_license';
@@ -263,8 +264,7 @@ export function ChatBody({
                   }}
                   onFeedback={handleFeedback}
                   onRegenerate={(message) => {
-                    const indexOf = messages.indexOf(message);
-                    next(messages.slice(0, indexOf));
+                    next(reverseToLastUserMessage(messages, message));
                   }}
                   onSendTelemetry={(eventWithPayload) =>
                     sendEvent(chatService.analytics, eventWithPayload)
@@ -410,3 +410,19 @@ export function ChatBody({
     </EuiFlexGroup>
   );
 }
+
+// Exported for testing only
+export function reverseToLastUserMessage(messages: Message[], message: Message) {
+  // Drop messages after and including the one marked for regeneration
+  const indexOf = messages.indexOf(message);
+  const previousMessages = messages.slice(0, indexOf);
+
+  // Go back to the last written user message to fully regenerate function calls
+  const lastUserMessageIndex = findLastIndex(
+    previousMessages,
+    (aMessage: Message) => aMessage.message.role === 'user' && !aMessage.message.name
+  );
+  const nextMessages = previousMessages.slice(0, lastUserMessageIndex + 1);
+
+  return nextMessages;
+}