diff --git a/source/extensions/stat_sinks/metrics_service/config.cc b/source/extensions/stat_sinks/metrics_service/config.cc
index 234b46b37740..22e9e58fad1f 100644
--- a/source/extensions/stat_sinks/metrics_service/config.cc
+++ b/source/extensions/stat_sinks/metrics_service/config.cc
@@ -29,7 +29,7 @@ Stats::SinkPtr MetricsServiceSinkFactory::createStatsSink(const Protobuf::Messag
               grpc_service, server.stats(), false),
           server.threadLocal(), server.localInfo());
 
-  return std::make_unique<MetricsServiceSink>(grpc_metrics_streamer);
+  return std::make_unique<MetricsServiceSink>(grpc_metrics_streamer, server.timeSource());
 }
 
 ProtobufTypes::MessagePtr MetricsServiceSinkFactory::createEmptyConfigProto() {
diff --git a/source/extensions/stat_sinks/metrics_service/grpc_metrics_service_impl.cc b/source/extensions/stat_sinks/metrics_service/grpc_metrics_service_impl.cc
index 19263feebb2f..a2ba3c619389 100644
--- a/source/extensions/stat_sinks/metrics_service/grpc_metrics_service_impl.cc
+++ b/source/extensions/stat_sinks/metrics_service/grpc_metrics_service_impl.cc
@@ -16,15 +16,6 @@ namespace Extensions {
 namespace StatSinks {
 namespace MetricsService {
 
-namespace {
-// TODO(#4160): use TimeSource::systemTime() rather than directly reading the system-clock.
-int64_t getUnixMillisForNow() {
-  return std::chrono::duration_cast<std::chrono::milliseconds>(
-             std::chrono::system_clock::now().time_since_epoch())
-      .count();
-}
-} // namespace
-
 GrpcMetricsStreamerImpl::GrpcMetricsStreamerImpl(Grpc::AsyncClientFactoryPtr&& factory,
                                                  ThreadLocal::SlotAllocator& tls,
                                                  const LocalInfo::LocalInfo& local_info)
@@ -70,15 +61,19 @@ void GrpcMetricsStreamerImpl::ThreadLocalStreamer::send(
   }
 }
 
-MetricsServiceSink::MetricsServiceSink(const GrpcMetricsStreamerSharedPtr& grpc_metrics_streamer)
-    : grpc_metrics_streamer_(grpc_metrics_streamer) {}
+MetricsServiceSink::MetricsServiceSink(const GrpcMetricsStreamerSharedPtr& grpc_metrics_streamer,
+                                       TimeSource& time_source)
+    : grpc_metrics_streamer_(grpc_metrics_streamer), time_source_(time_source) {}
 
 void MetricsServiceSink::flushCounter(const Stats::Counter& counter) {
   io::prometheus::client::MetricFamily* metrics_family = message_.add_envoy_metrics();
   metrics_family->set_type(io::prometheus::client::MetricType::COUNTER);
   metrics_family->set_name(counter.name());
   auto* metric = metrics_family->add_metric();
-  metric->set_timestamp_ms(getUnixMillisForNow());
+  metric->set_timestamp_ms(
+      std::chrono::duration_cast<std::chrono::milliseconds>(time_source_.systemTime().currentTime())
+          .time_since_epoch()
+          .count());
   auto* counter_metric = metric->mutable_counter();
   counter_metric->set_value(counter.value());
 }
@@ -88,7 +83,10 @@ void MetricsServiceSink::flushGauge(const Stats::Gauge& gauge) {
   metrics_family->set_type(io::prometheus::client::MetricType::GAUGE);
   metrics_family->set_name(gauge.name());
   auto* metric = metrics_family->add_metric();
-  metric->set_timestamp_ms(getUnixMillisForNow());
+  metric->set_timestamp_ms(
+      std::chrono::duration_cast<std::chrono::milliseconds>(time_source_.systemTime().currentTime())
+          .time_since_epoch()
+          .count());
   auto* gauage_metric = metric->mutable_gauge();
   gauage_metric->set_value(gauge.value());
 }
@@ -97,7 +95,10 @@ void MetricsServiceSink::flushHistogram(const Stats::ParentHistogram& histogram)
   metrics_family->set_type(io::prometheus::client::MetricType::SUMMARY);
   metrics_family->set_name(histogram.name());
   auto* metric = metrics_family->add_metric();
-  metric->set_timestamp_ms(getUnixMillisForNow());
+  metric->set_timestamp_ms(
+      std::chrono::duration_cast<std::chrono::milliseconds>(time_source_.systemTime().currentTime())
+          .time_since_epoch()
+          .count());
   auto* summary_metric = metric->mutable_summary();
   const Stats::HistogramStatistics& hist_stats = histogram.intervalStatistics();
   for (size_t i = 0; i < hist_stats.supportedQuantiles().size(); i++) {
diff --git a/source/extensions/stat_sinks/metrics_service/grpc_metrics_service_impl.h b/source/extensions/stat_sinks/metrics_service/grpc_metrics_service_impl.h
index b27792652d78..b250c9852981 100644
--- a/source/extensions/stat_sinks/metrics_service/grpc_metrics_service_impl.h
+++ b/source/extensions/stat_sinks/metrics_service/grpc_metrics_service_impl.h
@@ -122,6 +122,7 @@ class MetricsServiceSink : public Stats::Sink {
 private:
   GrpcMetricsStreamerSharedPtr grpc_metrics_streamer_;
   envoy::service::metrics::v2::StreamMetricsMessage message_;
+  TimeSource& time_source_;
 };
 
 } // namespace MetricsService