diff --git a/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/src/TelemetryPartA.cs b/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/src/TelemetryPartA.cs
index 755ea04dd5915..39b2e405a0460 100644
--- a/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/src/TelemetryPartA.cs
+++ b/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/src/TelemetryPartA.cs
@@ -18,6 +18,7 @@ namespace Azure.Monitor.OpenTelemetry.Exporter
     /// </summary>
     internal class TelemetryPartA
     {
+        private const string DateTimeFormat = "yyyy-MM-ddTHH:mm:ss.fffffffZ";
         private static readonly IReadOnlyDictionary<TelemetryType, string> PartA_Name_Mapping = new Dictionary<TelemetryType, string>
         {
             [TelemetryType.Request] = "Request",
@@ -32,7 +33,7 @@ internal class TelemetryPartA
 
         internal static TelemetryItem GetTelemetryItem(Activity activity, Resource resource, string instrumentationKey)
         {
-            TelemetryItem telemetryItem = new TelemetryItem(PartA_Name_Mapping[activity.GetTelemetryType()], activity.StartTimeUtc.ToString(CultureInfo.InvariantCulture))
+            TelemetryItem telemetryItem = new TelemetryItem(PartA_Name_Mapping[activity.GetTelemetryType()], FormatUtcTimestamp(activity.StartTimeUtc))
             {
                 InstrumentationKey = instrumentationKey
             };
@@ -55,7 +56,7 @@ internal static TelemetryItem GetTelemetryItem(Activity activity, Resource resou
         internal static TelemetryItem GetTelemetryItem(LogRecord logRecord, string instrumentationKey)
         {
             var name = PartA_Name_Mapping[TelemetryType.Message];
-            var time = logRecord.Timestamp.ToString(CultureInfo.InvariantCulture);
+            var time = FormatUtcTimestamp(logRecord.Timestamp);
 
             TelemetryItem telemetryItem = new TelemetryItem(name, time)
             {
@@ -122,5 +123,10 @@ internal static void InitRoleInfo(Resource resource)
                 RoleName = serviceName;
             }
         }
+
+        internal static string FormatUtcTimestamp(System.DateTime utcTimestamp)
+        {
+            return utcTimestamp.ToString(DateTimeFormat, CultureInfo.InvariantCulture);
+        }
     }
 }
diff --git a/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/tests/Azure.Monitor.OpenTelemetry.Exporter.Tests/TelemetryPartATests.cs b/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/tests/Azure.Monitor.OpenTelemetry.Exporter.Tests/TelemetryPartATests.cs
index c35cbd499fc83..45f7102f20388 100644
--- a/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/tests/Azure.Monitor.OpenTelemetry.Exporter.Tests/TelemetryPartATests.cs
+++ b/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/tests/Azure.Monitor.OpenTelemetry.Exporter.Tests/TelemetryPartATests.cs
@@ -116,7 +116,7 @@ public void GeneratePartAEnvelope_DefaultActivity_DefaultResource()
             var telemetryItem = TelemetryPartA.GetTelemetryItem(activity, resource, null);
 
             Assert.Equal("RemoteDependency", telemetryItem.Name);
-            Assert.Equal(activity.StartTimeUtc.ToString(CultureInfo.InvariantCulture), telemetryItem.Time);
+            Assert.Equal(TelemetryPartA.FormatUtcTimestamp(activity.StartTimeUtc), telemetryItem.Time);
             Assert.StartsWith("unknown_service", telemetryItem.Tags[ContextTagKeys.AiCloudRole.ToString()]);
             Assert.Null(telemetryItem.Tags[ContextTagKeys.AiCloudRoleInstance.ToString()]);
             Assert.NotNull(telemetryItem.Tags[ContextTagKeys.AiOperationId.ToString()]);
@@ -133,7 +133,7 @@ public void GeneratePartAEnvelope_Activity_WithResource()
             var telemetryItem = TelemetryPartA.GetTelemetryItem(activity, resource, null);
 
             Assert.Equal("RemoteDependency", telemetryItem.Name);
-            Assert.Equal(activity.StartTimeUtc.ToString(CultureInfo.InvariantCulture), telemetryItem.Time);
+            Assert.Equal(TelemetryPartA.FormatUtcTimestamp(activity.StartTimeUtc), telemetryItem.Time);
             Assert.Equal("my-service", telemetryItem.Tags[ContextTagKeys.AiCloudRole.ToString()]);
             Assert.Equal("my-instance", telemetryItem.Tags[ContextTagKeys.AiCloudRoleInstance.ToString()]);
             Assert.Equal(activity.TraceId.ToHexString(), telemetryItem.Tags[ContextTagKeys.AiOperationId.ToString()]);