diff --git a/app/src/hooks/useBrowserstackGroupId.ts b/app/src/hooks/useBrowserstackGroupId.ts
new file mode 100644
index 0000000000..6db5d2d222
--- /dev/null
+++ b/app/src/hooks/useBrowserstackGroupId.ts
@@ -0,0 +1,31 @@
+import { useEffect } from "react";
+import { useSelector } from "react-redux";
+import { getUserBrowserstackGroupId } from "store/features/billing/selectors";
+
+declare global {
+  interface Window {
+    currentlyActiveBrowserstackGroupId: string | null | undefined;
+  }
+}
+
+/**
+ * Exposes the signed-in user's BrowserStack group id on `window`, mirroring
+ * the existing `window.currentlyActiveWorkspace*` global pattern. The BS EDS
+ * integration (which ships via the requestly-cloud `webapp` analytics overlay,
+ * not this repo's `modules/analytics`) reads this global and stamps it as a
+ * top-level `data.group_id` field on every EDS event — flowing the same way as
+ * `browserstack_user_id`. This hook keeps the value in sync from the billing
+ * store; it is the interceptor-side source, analogous to how the auth handler
+ * exposes `browserstackId`.
+ *
+ * Group is a property of the USER (not the workspace) — sourced from the user's
+ * BS-linked billing team (`browserstackGroupId`). Feeds BrowserStack Usage
+ * Reports group attribution. See RQ-4675 and the track design doc.
+ */
+export const useBrowserstackGroupId = () => {
+  const browserstackGroupId = useSelector(getUserBrowserstackGroupId);
+
+  useEffect(() => {
+    window.currentlyActiveBrowserstackGroupId = browserstackGroupId ?? null;
+  }, [browserstackGroupId]);
+};
diff --git a/app/src/layouts/AppLayout/index.tsx b/app/src/layouts/AppLayout/index.tsx
index 6235ac5bb5..5dc62efac0 100644
--- a/app/src/layouts/AppLayout/index.tsx
+++ b/app/src/layouts/AppLayout/index.tsx
@@ -23,6 +23,7 @@ import AutomationNotAllowedNotice from "components/misc/notices/AutomationNotAll
 import { useIsExtensionEnabled } from "hooks";
 import { LazyMotion, domMax } from "framer-motion";
 import { useBillingTeamsListener } from "backend/billing/hooks/useBillingTeamsListener";
+import { useBrowserstackGroupId } from "hooks/useBrowserstackGroupId";
 import ThemeProvider from "lib/design-system-v2/helpers/ThemeProvider";
 import { InitImplicitWidgetConfigHandler } from "components/features/rules/TestThisRule";
 import APP_CONSTANTS from "config/constants";
@@ -45,6 +46,7 @@ const App: React.FC = () => {
   useGeoLocation();
   useIsExtensionEnabled();
   useBillingTeamsListener();
+  useBrowserstackGroupId();
   useAppLanguageObserver();
   // useInitializeNewUserSessionRecordingConfig();
 
diff --git a/app/src/store/features/billing/selectors.test.ts b/app/src/store/features/billing/selectors.test.ts
new file mode 100644
index 0000000000..e3f3cd6fd0
--- /dev/null
+++ b/app/src/store/features/billing/selectors.test.ts
@@ -0,0 +1,69 @@
+import { describe, it, expect } from "vitest";
+
+import { BillingTeamDetails, BillingTeamRoles } from "features/settings/components/BillingTeam/types";
+import { pickUserBrowserstackGroupId } from "./selectors";
+
+const UID = "user-123";
+
+const team = (overrides: Partial<BillingTeamDetails>): BillingTeamDetails =>
+  ({
+    id: "team-1",
+    name: "Team",
+    description: "",
+    owner: "owner",
+    subscriptionDetails: {},
+    members: {},
+    seats: 5,
+    ...overrides,
+  } as BillingTeamDetails);
+
+describe("pickUserBrowserstackGroupId", () => {
+  it("returns the browserstackGroupId of the team the user is a member of", () => {
+    const teams = [
+      team({
+        id: "browserstack-777",
+        browserstackGroupId: "777",
+        members: { [UID]: { role: BillingTeamRoles.Admin, joiningDate: 0 } },
+      }),
+    ];
+    expect(pickUserBrowserstackGroupId(teams, UID)).toBe("777");
+  });
+
+  it("prefers the team the user is a MEMBER of over a domain-matched team", () => {
+    const teams = [
+      // domain-matched team the listener also pulls in — user is NOT a member
+      team({ id: "browserstack-111", browserstackGroupId: "111", members: {} }),
+      // the user's actual team
+      team({
+        id: "browserstack-222",
+        browserstackGroupId: "222",
+        members: { [UID]: { role: BillingTeamRoles.Member, joiningDate: 0 } },
+      }),
+    ];
+    expect(pickUserBrowserstackGroupId(teams, UID)).toBe("222");
+  });
+
+  it("falls back to any team carrying a browserstackGroupId when the user is not a member of one", () => {
+    const teams = [
+      team({ id: "browserstack-333", browserstackGroupId: "333", members: {} }),
+    ];
+    expect(pickUserBrowserstackGroupId(teams, UID)).toBe("333");
+  });
+
+  it("ignores non-BrowserStack billing teams (no browserstackGroupId)", () => {
+    const teams = [
+      team({ id: "stripe-team", members: { [UID]: { role: BillingTeamRoles.Manager, joiningDate: 0 } } }),
+    ];
+    expect(pickUserBrowserstackGroupId(teams, UID)).toBeNull();
+  });
+
+  it("returns null when there are no billing teams", () => {
+    expect(pickUserBrowserstackGroupId([], UID)).toBeNull();
+    expect(pickUserBrowserstackGroupId(undefined, UID)).toBeNull();
+  });
+
+  it("returns null when there is no signed-in uid", () => {
+    const teams = [team({ browserstackGroupId: "999", members: {} })];
+    expect(pickUserBrowserstackGroupId(teams, undefined)).toBeNull();
+  });
+});
diff --git a/app/src/store/features/billing/selectors.ts b/app/src/store/features/billing/selectors.ts
index 4c5a0ddf54..e9a1daf632 100644
--- a/app/src/store/features/billing/selectors.ts
+++ b/app/src/store/features/billing/selectors.ts
@@ -1,5 +1,6 @@
 import { BillingTeamDetails } from "features/settings/components/BillingTeam/types";
 import { ReducerKeys } from "store/constants";
+import { getUserAuthDetails } from "store/slices/global/user/selectors";
 import { RootState } from "store/types";
 
 export const getAvailableBillingTeams = (state: RootState): BillingTeamDetails[] => {
@@ -32,3 +33,45 @@ export const getBillingTeamMemberById = (billingId: string, memberId: string) =>
 export const getIsBillingTeamsLoading = (state: RootState): boolean => {
   return state[ReducerKeys.BILLING].isBillingTeamsLoading;
 };
+
+/**
+ * Pure resolver for the signed-in user's BrowserStack group id from their
+ * billing teams. A BrowserStack-synced user belongs to exactly one
+ * `browserstack-<groupId>` billing team (requestly-cloud userSync guarantees
+ * this — see the design doc), so we prefer a team the user is an actual
+ * MEMBER of (over domain-matched teams the billing listener also pulls in),
+ * falling back to any team carrying a `browserstackGroupId`. Returns `null`
+ * when the user has no BS-linked billing team (email/Firebase-only or
+ * unlinked). Extracted from the selector so it can be unit-tested without a
+ * full RootState. See RQ-4675.
+ */
+export const pickUserBrowserstackGroupId = (
+  billingTeams: BillingTeamDetails[] | undefined,
+  uid: string | undefined
+): string | null => {
+  if (!uid || !billingTeams?.length) {
+    return null;
+  }
+
+  const memberTeam = billingTeams.find(
+    (team) => Boolean(team.browserstackGroupId) && Boolean(team.members) && uid in team.members
+  );
+  if (memberTeam?.browserstackGroupId) {
+    return memberTeam.browserstackGroupId;
+  }
+
+  const anyTeamWithGroup = billingTeams.find((team) => Boolean(team.browserstackGroupId));
+  return anyTeamWithGroup?.browserstackGroupId ?? null;
+};
+
+/**
+ * The signed-in user's BrowserStack group id (from their BS-linked billing
+ * team), or `null`. Feeds BrowserStack Usage Reports group attribution
+ * (RQ-4675) via `useBrowserstackGroupId` → the analytics enrichment choke-point.
+ */
+export const getUserBrowserstackGroupId = (state: RootState): string | null => {
+  return pickUserBrowserstackGroupId(
+    getAvailableBillingTeams(state),
+    getUserAuthDetails(state)?.details?.profile?.uid
+  );
+};