diff --git a/apps/reports/services/aggregation.py b/apps/reports/services/aggregation.py
index 4137930..a510ac9 100644
--- a/apps/reports/services/aggregation.py
+++ b/apps/reports/services/aggregation.py
@@ -387,31 +387,57 @@ def build_chart_report(actor, raw_filters) -> dict:
     filters = load_report_filters(actor, raw_filters)
     entries = list(_base_queryset(filters))
     summary = _summary_from_entries(entries)
-    buckets: dict[str, dict] = {}
+    grouped_entries: dict[str | None, list[TimeEntry]] = defaultdict(list)
+    if filters.is_workspace_scope and not filters.user_id:
+        for entry in entries:
+            grouped_entries[str(entry.user_id)].append(entry)
+    else:
+        grouped_entries[filters.user_id] = entries
 
-    for entry in entries:
-        local_start = _localize_datetime(entry.start_time)
-        bucket_id, bucket_date = _bucket_key(filters, local_start)
-        bucket = buckets.setdefault(
-            bucket_id,
+    serialized_series = []
+    for _, series_entries in sorted(
+        grouped_entries.items(),
+        key=lambda item: _user_display(item[1][0].user).lower() if item[1] else "",
+    ):
+        if not series_entries:
+            continue
+
+        buckets: dict[str, dict] = {}
+        for entry in series_entries:
+            local_start = _localize_datetime(entry.start_time)
+            bucket_id, bucket_date = _bucket_key(filters, local_start)
+            bucket = buckets.setdefault(
+                bucket_id,
+                {
+                    "bucket_key": bucket_id,
+                    "bucket_label": _bucket_label(filters, bucket_date),
+                    "total_seconds": 0,
+                    "total_duration": "00:00:00",
+                },
+            )
+            bucket["total_seconds"] += get_entry_duration_seconds(entry)
+
+        serialized_buckets = []
+        for bucket in sorted(buckets.values(), key=lambda item: item["bucket_key"]):
+            bucket["total_duration"] = _format_duration_seconds(bucket["total_seconds"])
+            serialized_buckets.append(bucket)
+
+        user = series_entries[0].user
+        serialized_series.append(
             {
-                "bucket_key": bucket_id,
-                "bucket_label": _bucket_label(filters, bucket_date),
-                "total_seconds": 0,
-                "total_duration": "00:00:00",
-            },
+                "user": {
+                    "id": str(user.id),
+                    "name": _user_display(user),
+                    "mobile": user.mobile,
+                },
+                "buckets": serialized_buckets,
+            }
         )
-        bucket["total_seconds"] += get_entry_duration_seconds(entry)
-
-    serialized_buckets = []
-    for bucket in sorted(buckets.values(), key=lambda item: item["bucket_key"]):
-        bucket["total_duration"] = _format_duration_seconds(bucket["total_seconds"])
-        serialized_buckets.append(bucket)
 
     return {
         "scope": _scope_payload(filters),
         "summary": summary,
-        "buckets": serialized_buckets,
+        "series": serialized_series,
     }
 
 
diff --git a/apps/reports/tests/test_views.py b/apps/reports/tests/test_views.py
index 27587c2..07e8d8f 100644
--- a/apps/reports/tests/test_views.py
+++ b/apps/reports/tests/test_views.py
@@ -100,6 +100,28 @@ class ReportViewTests(APITestCase):
 
         self.assertEqual(response.status_code, 200)
         self.assertEqual(response.data["summary"]["total_duration"], "01:00:00")
+        self.assertEqual(len(response.data["series"]), 1)
+        self.assertEqual(response.data["series"][0]["user"]["id"], str(self.member.id))
+
+    def test_admin_chart_without_user_filter_returns_series_for_all_users(self):
+        self.client.force_authenticate(user=self.admin)
+
+        with patch(
+            "apps.reports.services.aggregation.timezone.localdate",
+            return_value=date(2026, 4, 20),
+        ):
+            response = self.client.get(
+                "/api/reports/chart/",
+                {"workspace": str(self.workspace.id), "period": "this_month"},
+            )
+
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.data["summary"]["total_duration"], "03:00:00")
+        self.assertEqual(len(response.data["series"]), 2)
+        self.assertEqual(
+            {series["user"]["id"] for series in response.data["series"]},
+            {str(self.owner.id), str(self.member.id)},
+        )
 
     def test_admin_can_request_combined_table_report(self):
         self.client.force_authenticate(user=self.admin)