diff --git a/shell/common/vsync_waiter.cc b/shell/common/vsync_waiter.cc
index bfbd64c1338d5..c2806d5b7d338 100644
--- a/shell/common/vsync_waiter.cc
+++ b/shell/common/vsync_waiter.cc
@@ -7,8 +7,10 @@
 #include "flow/frame_timings.h"
 #include "flutter/fml/task_runner.h"
 #include "flutter/fml/trace_event.h"
+#include "fml/logging.h"
 #include "fml/message_loop_task_queues.h"
 #include "fml/task_queue_id.h"
+#include "fml/time/time_point.h"
 
 namespace flutter {
 
@@ -95,6 +97,8 @@ void VsyncWaiter::ScheduleSecondaryCallback(uintptr_t id,
 void VsyncWaiter::FireCallback(fml::TimePoint frame_start_time,
                                fml::TimePoint frame_target_time,
                                bool pause_secondary_tasks) {
+  FML_DCHECK(fml::TimePoint::Now() >= frame_start_time);
+
   Callback callback;
   std::vector<fml::closure> secondary_callbacks;
 
@@ -137,7 +141,7 @@ void VsyncWaiter::FireCallback(fml::TimePoint frame_start_time,
       ui_task_queue_id = task_runners_.GetUITaskRunner()->GetTaskQueueId();
     }
 
-    task_runners_.GetUITaskRunner()->PostTaskForTime(
+    task_runners_.GetUITaskRunner()->PostTask(
         [ui_task_queue_id, callback, flow_identifier, frame_start_time,
          frame_target_time, pause_secondary_tasks]() {
           FML_TRACE_EVENT("flutter", kVsyncTraceName, "StartTime",
@@ -151,8 +155,7 @@ void VsyncWaiter::FireCallback(fml::TimePoint frame_start_time,
           if (pause_secondary_tasks) {
             ResumeDartMicroTasks(ui_task_queue_id);
           }
-        },
-        frame_start_time);
+        });
   }
 
   for (auto& secondary_callback : secondary_callbacks) {
diff --git a/shell/common/vsync_waiter.h b/shell/common/vsync_waiter.h
index 998789ef5ca3d..b381f432a9bca 100644
--- a/shell/common/vsync_waiter.h
+++ b/shell/common/vsync_waiter.h
@@ -65,6 +65,8 @@ class VsyncWaiter : public std::enable_shared_from_this<VsyncWaiter> {
   // as AwaitVSync().
   virtual void AwaitVSyncForSecondaryCallback() { AwaitVSync(); }
 
+  // Schedules the callback on the UI task runner. Needs to be invoked as close
+  // to the `frame_start_time` as possible.
   void FireCallback(fml::TimePoint frame_start_time,
                     fml::TimePoint frame_target_time,
                     bool pause_secondary_tasks = true);
diff --git a/shell/common/vsync_waiter_fallback.cc b/shell/common/vsync_waiter_fallback.cc
index 8bf51c5ce2f4e..120e9a78551de 100644
--- a/shell/common/vsync_waiter_fallback.cc
+++ b/shell/common/vsync_waiter_fallback.cc
@@ -4,7 +4,10 @@
 
 #include "flutter/shell/common/vsync_waiter_fallback.h"
 
+#include <memory>
+
 #include "flutter/fml/logging.h"
+#include "flutter/fml/message_loop.h"
 #include "flutter/fml/trace_event.h"
 
 namespace flutter {
@@ -35,11 +38,20 @@ void VsyncWaiterFallback::AwaitVSync() {
 
   constexpr fml::TimeDelta kSingleFrameInterval =
       fml::TimeDelta::FromSecondsF(1.0 / 60.0);
-
-  auto next =
+  auto frame_start_time =
       SnapToNextTick(fml::TimePoint::Now(), phase_, kSingleFrameInterval);
-
-  FireCallback(next, next + kSingleFrameInterval, !for_testing_);
+  auto frame_target_time = frame_start_time + kSingleFrameInterval;
+  std::weak_ptr<VsyncWaiterFallback> weak_this =
+      std::static_pointer_cast<VsyncWaiterFallback>(shared_from_this());
+
+  task_runners_.GetUITaskRunner()->PostTaskForTime(
+      [frame_start_time, frame_target_time, weak_this]() {
+        if (auto vsync_waiter = weak_this.lock()) {
+          vsync_waiter->FireCallback(frame_start_time, frame_target_time,
+                                     !vsync_waiter->for_testing_);
+        }
+      },
+      frame_start_time);
 }
 
 }  // namespace flutter