diff --git a/x-pack/plugins/security_solution/common/experimental_features.ts b/x-pack/plugins/security_solution/common/experimental_features.ts
index 14b1bf8dc22dd..7d79c59fc6975 100644
--- a/x-pack/plugins/security_solution/common/experimental_features.ts
+++ b/x-pack/plugins/security_solution/common/experimental_features.ts
@@ -21,6 +21,7 @@ export const allowedExperimentalValues = Object.freeze({
   uebaEnabled: false,
   disableIsolationUIPendingStatuses: false,
   riskyHostsEnabled: false,
+  pendingActionResponsesWithAck: true,
 });
 
 type ExperimentalConfigKeys = Array<keyof ExperimentalFeatures>;
diff --git a/x-pack/plugins/security_solution/server/endpoint/routes/actions/status.test.ts b/x-pack/plugins/security_solution/server/endpoint/routes/actions/status.test.ts
index a8592f02691aa..e4dc9b049e2ba 100644
--- a/x-pack/plugins/security_solution/server/endpoint/routes/actions/status.test.ts
+++ b/x-pack/plugins/security_solution/server/endpoint/routes/actions/status.test.ts
@@ -87,7 +87,10 @@ describe('Endpoint Action Status', () => {
         logFactory: loggingSystemMock.create(),
         service: endpointAppContextService,
         config: () => Promise.resolve(createMockConfig()),
-        experimentalFeatures: parseExperimentalConfigValue(createMockConfig().enableExperimental),
+        experimentalFeatures: {
+          ...parseExperimentalConfigValue(createMockConfig().enableExperimental),
+          pendingActionResponsesWithAck: true,
+        },
       });
 
       getPendingStatus = async (reqParams?: any): Promise<jest.Mocked<KibanaResponseFactory>> => {
@@ -451,4 +454,321 @@ describe('Endpoint Action Status', () => {
       });
     });
   });
+
+  describe('response (when pendingActionResponsesWithAck is FALSE)', () => {
+    let endpointAppContextService: EndpointAppContextService;
+
+    // convenience for calling the route and handler for action status
+    let getPendingStatus: (reqParams?: any) => Promise<jest.Mocked<KibanaResponseFactory>>;
+    // convenience for injecting mock responses for actions index and responses
+    let havingActionsAndResponses: (
+      actions: MockAction[],
+      responses: MockResponse[],
+      endpointResponses?: MockEndpointResponse[]
+    ) => void;
+
+    beforeEach(() => {
+      const esClientMock = elasticsearchServiceMock.createScopedClusterClient();
+      const routerMock = httpServiceMock.createRouter();
+      endpointAppContextService = new EndpointAppContextService();
+      endpointAppContextService.setup(createMockEndpointAppContextServiceSetupContract());
+      endpointAppContextService.start(createMockEndpointAppContextServiceStartContract());
+
+      registerActionStatusRoutes(routerMock, {
+        logFactory: loggingSystemMock.create(),
+        service: endpointAppContextService,
+        config: () => Promise.resolve(createMockConfig()),
+        experimentalFeatures: {
+          ...parseExperimentalConfigValue(createMockConfig().enableExperimental),
+          pendingActionResponsesWithAck: false,
+        },
+      });
+
+      getPendingStatus = async (reqParams?: any): Promise<jest.Mocked<KibanaResponseFactory>> => {
+        const req = httpServerMock.createKibanaRequest(reqParams);
+        const mockResponse = httpServerMock.createResponseFactory();
+        const [, routeHandler]: [
+          RouteConfig<any, any, any, any>,
+          RequestHandler<any, any, any, any>
+        ] = routerMock.get.mock.calls.find(([{ path }]) => path.startsWith(ACTION_STATUS_ROUTE))!;
+        await routeHandler(
+          createRouteHandlerContext(esClientMock, savedObjectsClientMock.create()),
+          req,
+          mockResponse
+        );
+
+        return mockResponse;
+      };
+
+      havingActionsAndResponses = (
+        actions: MockAction[],
+        responses: MockResponse[],
+        endpointResponses?: MockEndpointResponse[]
+      ) => {
+        esClientMock.asCurrentUser.search = jest.fn().mockImplementation((req) => {
+          const size = req.size ? req.size : 10;
+          const items: any[] =
+            req.index === '.fleet-actions'
+              ? actions.splice(0, size)
+              : req.index === '.logs-endpoint.action.responses' && !!endpointResponses
+              ? endpointResponses
+              : responses.splice(0, size);
+
+          if (items.length > 0) {
+            return Promise.resolve(mockSearchResult(items.map((x) => x.build())));
+          } else {
+            return Promise.resolve(mockSearchResult());
+          }
+        });
+      };
+    });
+
+    afterEach(() => {
+      endpointAppContextService.stop();
+    });
+
+    it('should include total counts for large (more than a page) action counts', async () => {
+      const mockID = 'XYZABC-000';
+      const actions = [];
+      for (let i = 0; i < 1400; i++) {
+        // putting more than a single page of results in
+        actions.push(aMockAction().withAgent(mockID));
+      }
+      havingActionsAndResponses(actions, []);
+
+      const response = await getPendingStatus({
+        query: {
+          agent_ids: [mockID],
+        },
+      });
+
+      expect(response.ok).toBeCalled();
+      expect((response.ok.mock.calls[0][0]?.body as any)?.data).toHaveLength(1);
+      expect((response.ok.mock.calls[0][0]?.body as any)?.data[0].agent_id).toEqual(mockID);
+      expect((response.ok.mock.calls[0][0]?.body as any)?.data[0].pending_actions.isolate).toEqual(
+        0
+      );
+    });
+    it('should include a total count of a pending action', async () => {
+      const mockID = 'XYZABC-000';
+      havingActionsAndResponses(
+        [
+          aMockAction().withAgent(mockID).withAction('isolate'),
+          aMockAction().withAgent(mockID).withAction('isolate'),
+        ],
+        []
+      );
+      const response = await getPendingStatus({
+        query: {
+          agent_ids: [mockID],
+        },
+      });
+      expect(response.ok).toBeCalled();
+      expect((response.ok.mock.calls[0][0]?.body as any)?.data).toHaveLength(1);
+      expect((response.ok.mock.calls[0][0]?.body as any)?.data[0].agent_id).toEqual(mockID);
+      expect((response.ok.mock.calls[0][0]?.body as any)?.data[0].pending_actions.isolate).toEqual(
+        0
+      );
+    });
+    it('should show multiple pending actions, and their counts', async () => {
+      const mockID = 'XYZABC-000';
+      havingActionsAndResponses(
+        [
+          aMockAction().withAgent(mockID).withAction('isolate'),
+          aMockAction().withAgent(mockID).withAction('isolate'),
+          aMockAction().withAgent(mockID).withAction('isolate'),
+          aMockAction().withAgent(mockID).withAction('unisolate'),
+          aMockAction().withAgent(mockID).withAction('unisolate'),
+        ],
+        []
+      );
+      const response = await getPendingStatus({
+        query: {
+          agent_ids: [mockID],
+        },
+      });
+      expect(response.ok).toBeCalled();
+      expect((response.ok.mock.calls[0][0]?.body as any)?.data).toHaveLength(1);
+      expect((response.ok.mock.calls[0][0]?.body as any)?.data[0].agent_id).toEqual(mockID);
+      expect((response.ok.mock.calls[0][0]?.body as any)?.data[0].pending_actions.isolate).toEqual(
+        0
+      );
+      expect(
+        (response.ok.mock.calls[0][0]?.body as any)?.data[0].pending_actions.unisolate
+      ).toEqual(0);
+    });
+    it('should calculate correct pending counts from grouped/bulked actions', async () => {
+      const mockID = 'XYZABC-000';
+      havingActionsAndResponses(
+        [
+          aMockAction()
+            .withAgents([mockID, 'IRRELEVANT-OTHER-AGENT', 'ANOTHER-POSSIBLE-AGENT'])
+            .withAction('isolate'),
+          aMockAction().withAgents([mockID, 'YET-ANOTHER-AGENT-ID']).withAction('isolate'),
+          aMockAction().withAgents(['YET-ANOTHER-AGENT-ID']).withAction('isolate'), // one WITHOUT our agent-under-test
+        ],
+        []
+      );
+      const response = await getPendingStatus({
+        query: {
+          agent_ids: [mockID],
+        },
+      });
+      expect(response.ok).toBeCalled();
+      expect((response.ok.mock.calls[0][0]?.body as any)?.data).toHaveLength(1);
+      expect((response.ok.mock.calls[0][0]?.body as any)?.data[0].agent_id).toEqual(mockID);
+      expect((response.ok.mock.calls[0][0]?.body as any)?.data[0].pending_actions.isolate).toEqual(
+        0
+      );
+    });
+
+    it('should exclude actions that have responses from the pending count', async () => {
+      const mockAgentID = 'XYZABC-000';
+      const actionID = 'some-known-actionid';
+      havingActionsAndResponses(
+        [
+          aMockAction().withAgent(mockAgentID).withAction('isolate'),
+          aMockAction().withAgent(mockAgentID).withAction('isolate').withID(actionID),
+        ],
+        [aMockResponse(actionID, mockAgentID)]
+      );
+      (endpointAppContextService.getEndpointMetadataService as jest.Mock) = jest
+        .fn()
+        .mockReturnValue({
+          findHostMetadataForFleetAgents: jest.fn().mockResolvedValue([]),
+        });
+      const response = await getPendingStatus({
+        query: {
+          agent_ids: [mockAgentID],
+        },
+      });
+      expect(response.ok).toBeCalled();
+      expect((response.ok.mock.calls[0][0]?.body as any)?.data).toHaveLength(1);
+      expect((response.ok.mock.calls[0][0]?.body as any)?.data[0].agent_id).toEqual(mockAgentID);
+      expect((response.ok.mock.calls[0][0]?.body as any)?.data[0].pending_actions.isolate).toEqual(
+        0
+      );
+    });
+    it('should have accurate counts for multiple agents, bulk actions, and responses', async () => {
+      const agentOne = 'XYZABC-000';
+      const agentTwo = 'DEADBEEF';
+      const agentThree = 'IDIDIDID';
+
+      const actionTwoID = 'ID-TWO';
+      havingActionsAndResponses(
+        [
+          aMockAction().withAgents([agentOne, agentTwo, agentThree]).withAction('isolate'),
+          aMockAction()
+            .withAgents([agentTwo, agentThree])
+            .withAction('isolate')
+            .withID(actionTwoID),
+          aMockAction().withAgents([agentThree]).withAction('isolate'),
+        ],
+        [aMockResponse(actionTwoID, agentThree)]
+      );
+      (endpointAppContextService.getEndpointMetadataService as jest.Mock) = jest
+        .fn()
+        .mockReturnValue({
+          findHostMetadataForFleetAgents: jest.fn().mockResolvedValue([]),
+        });
+      const response = await getPendingStatus({
+        query: {
+          agent_ids: [agentOne, agentTwo, agentThree],
+        },
+      });
+      expect(response.ok).toBeCalled();
+      expect((response.ok.mock.calls[0][0]?.body as any)?.data).toHaveLength(3);
+      expect((response.ok.mock.calls[0][0]?.body as any)?.data).toContainEqual({
+        agent_id: agentOne,
+        pending_actions: {
+          isolate: 0,
+        },
+      });
+      expect((response.ok.mock.calls[0][0]?.body as any)?.data).toContainEqual({
+        agent_id: agentTwo,
+        pending_actions: {
+          isolate: 0,
+        },
+      });
+      expect((response.ok.mock.calls[0][0]?.body as any)?.data).toContainEqual({
+        agent_id: agentThree,
+        pending_actions: {
+          isolate: 0,
+        },
+      });
+    });
+
+    describe('with endpoint response index', () => {
+      it('should include a total count of a pending action response', async () => {
+        const mockAgentId = 'XYZABC-000';
+        const actionIds = ['action_id_0', 'action_id_1'];
+        havingActionsAndResponses(
+          [
+            aMockAction().withAgent(mockAgentId).withAction('isolate').withID(actionIds[0]),
+            aMockAction().withAgent(mockAgentId).withAction('isolate').withID(actionIds[1]),
+          ],
+          [
+            aMockResponse(actionIds[0], mockAgentId, true),
+            aMockResponse(actionIds[1], mockAgentId, true),
+          ]
+        );
+        (endpointAppContextService.getEndpointMetadataService as jest.Mock) = jest
+          .fn()
+          .mockReturnValue({
+            findHostMetadataForFleetAgents: jest.fn().mockResolvedValue([]),
+          });
+        const response = await getPendingStatus({
+          query: {
+            agent_ids: [mockAgentId],
+          },
+        });
+        expect(response.ok).toBeCalled();
+        expect((response.ok.mock.calls[0][0]?.body as any)?.data).toHaveLength(1);
+        expect((response.ok.mock.calls[0][0]?.body as any)?.data[0].agent_id).toEqual(mockAgentId);
+        expect(
+          (response.ok.mock.calls[0][0]?.body as any)?.data[0].pending_actions.isolate
+        ).toEqual(0);
+      });
+
+      it('should show multiple pending action responses, and their counts', async () => {
+        const mockAgentID = 'XYZABC-000';
+        const actionIds = ['ack_0', 'ack_1', 'ack_2', 'ack_3', 'ack_4'];
+        havingActionsAndResponses(
+          [
+            aMockAction().withAgent(mockAgentID).withAction('isolate').withID(actionIds[0]),
+            aMockAction().withAgent(mockAgentID).withAction('isolate').withID(actionIds[1]),
+            aMockAction().withAgent(mockAgentID).withAction('isolate').withID(actionIds[2]),
+            aMockAction().withAgent(mockAgentID).withAction('unisolate').withID(actionIds[3]),
+            aMockAction().withAgent(mockAgentID).withAction('unisolate').withID(actionIds[4]),
+          ],
+          [
+            aMockResponse(actionIds[0], mockAgentID, true),
+            aMockResponse(actionIds[1], mockAgentID, true),
+            aMockResponse(actionIds[2], mockAgentID, true),
+            aMockResponse(actionIds[3], mockAgentID, true),
+            aMockResponse(actionIds[4], mockAgentID, true),
+          ]
+        );
+        (endpointAppContextService.getEndpointMetadataService as jest.Mock) = jest
+          .fn()
+          .mockReturnValue({
+            findHostMetadataForFleetAgents: jest.fn().mockResolvedValue([]),
+          });
+        const response = await getPendingStatus({
+          query: {
+            agent_ids: [mockAgentID],
+          },
+        });
+        expect(response.ok).toBeCalled();
+        expect((response.ok.mock.calls[0][0]?.body as any)?.data).toHaveLength(1);
+        expect((response.ok.mock.calls[0][0]?.body as any)?.data[0].agent_id).toEqual(mockAgentID);
+        expect(
+          (response.ok.mock.calls[0][0]?.body as any)?.data[0].pending_actions.isolate
+        ).toEqual(0);
+        expect(
+          (response.ok.mock.calls[0][0]?.body as any)?.data[0].pending_actions.unisolate
+        ).toEqual(0);
+      });
+    });
+  });
 });
diff --git a/x-pack/plugins/security_solution/server/endpoint/routes/actions/status.ts b/x-pack/plugins/security_solution/server/endpoint/routes/actions/status.ts
index 4ba03bf220c21..32c709aef2b87 100644
--- a/x-pack/plugins/security_solution/server/endpoint/routes/actions/status.ts
+++ b/x-pack/plugins/security_solution/server/endpoint/routes/actions/status.ts
@@ -50,7 +50,8 @@ export const actionStatusRequestHandler = function (
     const response = await getPendingActionCounts(
       esClient,
       endpointContext.service.getEndpointMetadataService(),
-      agentIDs
+      agentIDs,
+      endpointContext.experimentalFeatures.pendingActionResponsesWithAck
     );
 
     return res.ok({
diff --git a/x-pack/plugins/security_solution/server/endpoint/services/actions.ts b/x-pack/plugins/security_solution/server/endpoint/services/actions.ts
index 8104c51068182..49805c1e29ed3 100644
--- a/x-pack/plugins/security_solution/server/endpoint/services/actions.ts
+++ b/x-pack/plugins/security_solution/server/endpoint/services/actions.ts
@@ -186,7 +186,8 @@ export const getPendingActionCounts = async (
   esClient: ElasticsearchClient,
   metadataService: EndpointMetadataService,
   /** The Fleet Agent IDs to be checked */
-  agentIDs: string[]
+  agentIDs: string[],
+  isPendingActionResponsesWithAckEnabled: boolean
 ): Promise<EndpointPendingActions[]> => {
   // retrieve the unexpired actions for the given hosts
   const recentActions = await esClient
@@ -254,11 +255,17 @@ export const getPendingActionCounts = async (
       pending_actions: pendingActions
         .map((a) => a.data.command)
         .reduce((acc, cur) => {
-          if (cur in acc) {
-            acc[cur] += 1;
+          if (!isPendingActionResponsesWithAckEnabled) {
+            acc[cur] = 0; // set pending counts to 0 when FF is disabled
           } else {
-            acc[cur] = 1;
+            // else do the usual counting
+            if (cur in acc) {
+              acc[cur] += 1;
+            } else {
+              acc[cur] = 1;
+            }
           }
+
           return acc;
         }, {} as EndpointPendingActions['pending_actions']),
     });
diff --git a/x-pack/plugins/security_solution/server/search_strategy/security_solution/factory/hosts/details/helpers.ts b/x-pack/plugins/security_solution/server/search_strategy/security_solution/factory/hosts/details/helpers.ts
index fbc51aa0360ce..918d3aadfd6e8 100644
--- a/x-pack/plugins/security_solution/server/search_strategy/security_solution/factory/hosts/details/helpers.ts
+++ b/x-pack/plugins/security_solution/server/search_strategy/security_solution/factory/hosts/details/helpers.ts
@@ -209,7 +209,8 @@ export const getHostEndpoint = async (
       ? getPendingActionCounts(
           esClient.asInternalUser,
           endpointContext.service.getEndpointMetadataService(),
-          [fleetAgentId]
+          [fleetAgentId],
+          endpointContext.experimentalFeatures.pendingActionResponsesWithAck
         )
           .then((results) => {
             return results[0].pending_actions;