diff --git a/x-pack/plugins/security_solution/public/assistant/get_comments/stream/stream_observable.ts b/x-pack/plugins/security_solution/public/assistant/get_comments/stream/stream_observable.ts
index b30be69b82cae..98828a598562a 100644
--- a/x-pack/plugins/security_solution/public/assistant/get_comments/stream/stream_observable.ts
+++ b/x-pack/plugins/security_solution/public/assistant/get_comments/stream/stream_observable.ts
@@ -48,6 +48,7 @@ export const getStreamObservable = (
                 `${API_ERROR}\n\n${JSON.parse(decoded).message}`
               : // all other responses are just strings (handled by subaction invokeStream)
                 decoded;
+
             chunks.push(content);
             observer.next({
               chunks,
diff --git a/x-pack/plugins/stack_connectors/server/connector_types/openai/openai.ts b/x-pack/plugins/stack_connectors/server/connector_types/openai/openai.ts
index 02ad7bcdec6a9..6961b5c5bc3b3 100644
--- a/x-pack/plugins/stack_connectors/server/connector_types/openai/openai.ts
+++ b/x-pack/plugins/stack_connectors/server/connector_types/openai/openai.ts
@@ -234,14 +234,19 @@ export class OpenAIConnector extends SubActionConnector<Config, Secrets> {
  * parses the proprietary OpenAI response into a string of the response text alone,
  * returning the response string to the stream
  */
-const transformToString = () =>
-  new Transform({
+const transformToString = () => {
+  let lineBuffer: string = '';
+
+  return new Transform({
     transform(chunk, encoding, callback) {
       const decoder = new TextDecoder();
       const encoder = new TextEncoder();
-      const nextChunk = decoder
-        .decode(chunk)
-        .split('\n')
+      const lines = decoder.decode(chunk).split('\n');
+      lines[0] = lineBuffer + lines[0];
+
+      lineBuffer = lines.pop() || '';
+
+      const nextChunk = lines
         // every line starts with "data: ", we remove it and are left with stringified JSON or the string "[DONE]"
         .map((str) => str.substring(6))
         // filter out empty lines and the "[DONE]" string
@@ -255,3 +260,4 @@ const transformToString = () =>
       callback(null, newChunk);
     },
   });
+};
diff --git a/x-pack/test/alerting_api_integration/common/plugins/actions_simulators/server/bedrock_simulation.ts b/x-pack/test/alerting_api_integration/common/plugins/actions_simulators/server/bedrock_simulation.ts
index bfa8c5cb0736f..29e77feb5edaf 100644
--- a/x-pack/test/alerting_api_integration/common/plugins/actions_simulators/server/bedrock_simulation.ts
+++ b/x-pack/test/alerting_api_integration/common/plugins/actions_simulators/server/bedrock_simulation.ts
@@ -7,6 +7,8 @@
 
 import http from 'http';
 
+import { EventStreamCodec } from '@smithy/eventstream-codec';
+import { fromUtf8, toUtf8 } from '@smithy/util-utf8';
 import { ProxyArgs, Simulator } from './simulator';
 
 export class BedrockSimulator extends Simulator {
@@ -27,6 +29,10 @@ export class BedrockSimulator extends Simulator {
       return BedrockSimulator.sendErrorResponse(response);
     }
 
+    if (request.url === '/model/anthropic.claude-v2/invoke-with-response-stream') {
+      return BedrockSimulator.sendStreamResponse(response);
+    }
+
     return BedrockSimulator.sendResponse(response);
   }
 
@@ -36,6 +42,14 @@ export class BedrockSimulator extends Simulator {
     response.end(JSON.stringify(bedrockSuccessResponse, null, 4));
   }
 
+  private static sendStreamResponse(response: http.ServerResponse) {
+    response.statusCode = 200;
+    response.setHeader('Content-Type', 'application/octet-stream');
+    response.setHeader('Transfer-Encoding', 'chunked');
+    response.write(encodeBedrockResponse('Hello world, what a unique string!'));
+    response.end();
+  }
+
   private static sendErrorResponse(response: http.ServerResponse) {
     response.statusCode = 422;
     response.setHeader('Content-Type', 'application/json;charset=UTF-8');
@@ -52,3 +66,20 @@ export const bedrockFailedResponse = {
   message:
     'Malformed input request: extraneous key [ooooo] is not permitted, please reformat your input and try again.',
 };
+
+function encodeBedrockResponse(completion: string) {
+  return new EventStreamCodec(toUtf8, fromUtf8).encode({
+    headers: {
+      ':event-type': { type: 'string', value: 'chunk' },
+      ':content-type': { type: 'string', value: 'application/json' },
+      ':message-type': { type: 'string', value: 'event' },
+    },
+    body: Uint8Array.from(
+      Buffer.from(
+        JSON.stringify({
+          bytes: Buffer.from(JSON.stringify({ completion })).toString('base64'),
+        })
+      )
+    ),
+  });
+}
diff --git a/x-pack/test/alerting_api_integration/security_and_spaces/group2/tests/actions/connector_types/bedrock.ts b/x-pack/test/alerting_api_integration/security_and_spaces/group2/tests/actions/connector_types/bedrock.ts
index 67053bef7801b..ff9bba40a228f 100644
--- a/x-pack/test/alerting_api_integration/security_and_spaces/group2/tests/actions/connector_types/bedrock.ts
+++ b/x-pack/test/alerting_api_integration/security_and_spaces/group2/tests/actions/connector_types/bedrock.ts
@@ -12,6 +12,7 @@ import {
   bedrockSuccessResponse,
 } from '@kbn/actions-simulators-plugin/server/bedrock_simulation';
 import { DEFAULT_TOKEN_LIMIT } from '@kbn/stack-connectors-plugin/common/bedrock/constants';
+import { PassThrough } from 'stream';
 import { FtrProviderContext } from '../../../../../common/ftr_provider_context';
 import { getUrlPrefix, ObjectRemover } from '../../../../../common/lib';
 
@@ -31,6 +32,7 @@ export default function bedrockTest({ getService }: FtrProviderContext) {
   const supertest = getService('supertest');
   const objectRemover = new ObjectRemover(supertest);
   const configService = getService('config');
+  const retry = getService('retry');
   const createConnector = async (apiUrl: string, spaceId?: string) => {
     const result = await supertest
       .post(`${getUrlPrefix(spaceId ?? 'default')}/api/actions/connector`)
@@ -407,6 +409,43 @@ export default function bedrockTest({ getService }: FtrProviderContext) {
               data: { message: bedrockSuccessResponse.completion },
             });
           });
+
+          it.only('should invoke stream with assistant AI body argument formatted to bedrock expectations', async () => {
+            await new Promise<void>((resolve, reject) => {
+              let responseBody: string = '';
+
+              const passThrough = new PassThrough();
+
+              supertest
+                .post(`/internal/elastic_assistant/actions/connector/${bedrockActionId}/_execute`)
+                .set('kbn-xsrf', 'foo')
+                .on('error', reject)
+                .send({
+                  params: {
+                    subAction: 'invokeStream',
+                    subActionParams: {
+                      messages: [
+                        {
+                          role: 'user',
+                          content: 'Hello world',
+                        },
+                      ],
+                    },
+                  },
+                  assistantLangChain: false,
+                })
+                .pipe(passThrough);
+
+              passThrough.on('data', (chunk) => {
+                responseBody += chunk.toString();
+              });
+
+              passThrough.on('end', () => {
+                expect(responseBody).to.eql('Hello world, what a unique string!');
+                resolve();
+              });
+            });
+          });
         });
       });