diff --git a/airflow-core/src/airflow/ui/src/layouts/Details/Gantt/GanttTimeline.tsx b/airflow-core/src/airflow/ui/src/layouts/Details/Gantt/GanttTimeline.tsx
index 43c28dba56b52..940a80854e29b 100644
--- a/airflow-core/src/airflow/ui/src/layouts/Details/Gantt/GanttTimeline.tsx
+++ b/airflow-core/src/airflow/ui/src/layouts/Details/Gantt/GanttTimeline.tsx
@@ -85,7 +85,7 @@ const toTooltipSummary = (
 
   return {
     child_states: null,
-    max_end_date: dayjs(segment.x[1]).toISOString(),
+    max_end_date: segment.end_when ?? dayjs(segment.x[1]).toISOString(),
     min_start_date: segment.start_when ?? dayjs(segment.x[0]).toISOString(),
     state: segment.state ?? null,
     task_display_name: segment.y,
diff --git a/airflow-core/src/airflow/ui/src/layouts/Details/Gantt/utils.test.ts b/airflow-core/src/airflow/ui/src/layouts/Details/Gantt/utils.test.ts
index d725dfc8be60d..92708a49c3875 100644
--- a/airflow-core/src/airflow/ui/src/layouts/Details/Gantt/utils.test.ts
+++ b/airflow-core/src/airflow/ui/src/layouts/Details/Gantt/utils.test.ts
@@ -257,6 +257,14 @@ describe("transformGanttData", () => {
     });
 
     expect(result).toHaveLength(2);
+    expect(result[0]).toMatchObject({
+      end_when: "2024-03-14T10:05:00+00:00",
+      state: "queued",
+    });
+    expect(result[1]).toMatchObject({
+      end_when: "2024-03-14T10:05:00+00:00",
+      state: "success",
+    });
     expect(result[0]?.state).toBe("queued");
     expect(result[1]?.state).toBe("success");
   });
diff --git a/airflow-core/src/airflow/ui/src/layouts/Details/Gantt/utils.ts b/airflow-core/src/airflow/ui/src/layouts/Details/Gantt/utils.ts
index 9502cd31e7843..62b9fff84b432 100644
--- a/airflow-core/src/airflow/ui/src/layouts/Details/Gantt/utils.ts
+++ b/airflow-core/src/airflow/ui/src/layouts/Details/Gantt/utils.ts
@@ -28,6 +28,8 @@ import { renderDuration } from "src/utils/datetimeUtils";
 import { buildTaskInstanceUrl } from "src/utils/links";
 
 export type GanttDataItem = {
+  /** Actual task execution end_date — consistent across all segments of the same try. */
+  end_when?: string | null;
   isGroup?: boolean | null;
   isMapped?: boolean | null;
   /** Source try times for tooltips (matches TaskInstance `*_when` fields). */
@@ -140,6 +142,7 @@ export const transformGanttData = ({
               ...(scheduledMs === undefined ? {} : { scheduled_when: scheduledDttm }),
               ...(queuedMs === undefined ? {} : { queued_when: queuedDttm }),
               ...(startDate === null ? {} : { start_when: startDate }),
+              ...(endDate === null ? {} : { end_when: endDate }),
             };
 
             let endMs: number;