diff --git a/sdk/monitor/azure-monitor-opentelemetry-exporter/CHANGELOG.md b/sdk/monitor/azure-monitor-opentelemetry-exporter/CHANGELOG.md
index 2ab49efeb43e..9b5e9fe3ea01 100644
--- a/sdk/monitor/azure-monitor-opentelemetry-exporter/CHANGELOG.md
+++ b/sdk/monitor/azure-monitor-opentelemetry-exporter/CHANGELOG.md
@@ -7,6 +7,8 @@
 ### Breaking Changes
 
 ### Bugs Fixed
+- Fix fallback logic when connection string is provided only via environment variable
+  ([#45252](https://github.com/Azure/azure-sdk-for-python/pull/45252))
 
 ### Other Changes
 
diff --git a/sdk/monitor/azure-monitor-opentelemetry-exporter/azure/monitor/opentelemetry/exporter/_connection_string_parser.py b/sdk/monitor/azure-monitor-opentelemetry-exporter/azure/monitor/opentelemetry/exporter/_connection_string_parser.py
index 2045a2b66c8e..df22912d6073 100644
--- a/sdk/monitor/azure-monitor-opentelemetry-exporter/azure/monitor/opentelemetry/exporter/_connection_string_parser.py
+++ b/sdk/monitor/azure-monitor-opentelemetry-exporter/azure/monitor/opentelemetry/exporter/_connection_string_parser.py
@@ -50,6 +50,9 @@ def _initialize(self) -> None:
         env_cs = self._parse_connection_string(os.getenv("APPLICATIONINSIGHTS_CONNECTION_STRING"))
         env_ikey = os.getenv("APPINSIGHTS_INSTRUMENTATIONKEY")
 
+        if not self._connection_string:
+            self._connection_string = os.getenv("APPLICATIONINSIGHTS_CONNECTION_STRING")
+
         # The priority of which value takes on the instrumentation key is:
         # 1. Key from explicitly passed in connection string
         # 2. Key from explicitly passed in instrumentation key