diff --git a/BASE/src/Microsoft.ApplicationInsights/Extensibility/TelemetryConfiguration.cs b/BASE/src/Microsoft.ApplicationInsights/Extensibility/TelemetryConfiguration.cs
index 5fdb3a10a..895e3196b 100644
--- a/BASE/src/Microsoft.ApplicationInsights/Extensibility/TelemetryConfiguration.cs
+++ b/BASE/src/Microsoft.ApplicationInsights/Extensibility/TelemetryConfiguration.cs
@@ -357,6 +357,11 @@ internal void SetCloudRole(string serviceName, string serviceInstanceId = null,
 
         internal FeatureMetricEmissionHelper InitializeFeatureReporter()
         {
+            if (string.IsNullOrEmpty(this.connectionString))
+            {
+                return this.FeatureReporter;
+            }
+
             var connectionString = Microsoft.ApplicationInsights.Internal.ConnectionString.Parse(this.ConnectionString);
             var ciKey = connectionString.GetNonRequired("InstrumentationKey");
             this.FeatureReporter = FeatureMetricEmissionHelper.GetOrCreate(ciKey, this.extensionVersion);
@@ -381,6 +386,16 @@ internal OpenTelemetrySdk Build()
                     return this.openTelemetrySdk;
                 }
 
+                // If no connection string was explicitly set, fall back to the environment variable.
+                if (string.IsNullOrEmpty(this.connectionString))
+                {
+                    var envConnectionString = Environment.GetEnvironmentVariable("APPLICATIONINSIGHTS_CONNECTION_STRING");
+                    if (!string.IsNullOrEmpty(envConnectionString))
+                    {
+                        this.connectionString = envConnectionString;
+                    }
+                }
+
                 Environment.SetEnvironmentVariable("OTEL_SDK_DISABLED", this.disableTelemetry ? "true" : "false");
 
                 this.openTelemetrySdk = OpenTelemetrySdk.Create(builder =>
@@ -388,7 +403,10 @@ internal OpenTelemetrySdk Build()
                     this.builderConfiguration(builder);
                     builder.SetAzureMonitorExporter(options =>
                     {
-                        options.ConnectionString = this.connectionString;
+                        if (!string.IsNullOrEmpty(this.connectionString))
+                        {
+                            options.ConnectionString = this.connectionString;
+                        }
 
                         if (this.tracesPerSecond.HasValue)
                         {
diff --git a/LOGGING/src/NLogTarget/ApplicationInsightsTarget.cs b/LOGGING/src/NLogTarget/ApplicationInsightsTarget.cs
index 47c108826..df61d9523 100644
--- a/LOGGING/src/NLogTarget/ApplicationInsightsTarget.cs
+++ b/LOGGING/src/NLogTarget/ApplicationInsightsTarget.cs
@@ -126,6 +126,11 @@ protected override void InitializeTarget()
             base.InitializeTarget();
 
             string connectionString = this.connectionStringLayout.Render(LogEventInfo.CreateNullEvent());
+            if (string.IsNullOrWhiteSpace(connectionString))
+            {
+                connectionString = Environment.GetEnvironmentVariable("APPLICATIONINSIGHTS_CONNECTION_STRING");
+            }
+
             if (string.IsNullOrWhiteSpace(connectionString))
             {
                 throw new NLogConfigurationException(ConnectionStringRequiredMessage);