diff --git a/sdk/cosmos/azure-cosmos/CHANGELOG.md b/sdk/cosmos/azure-cosmos/CHANGELOG.md
index 8cbf52e3f916..67d535bf6570 100644
--- a/sdk/cosmos/azure-cosmos/CHANGELOG.md
+++ b/sdk/cosmos/azure-cosmos/CHANGELOG.md
@@ -12,6 +12,7 @@
 * Fixed JVM `<clinit>` deadlock when multiple threads concurrently trigger Cosmos SDK class loading for the first time. - See [PR 48689](https://github.com/Azure/azure-sdk-for-java/pull/48689)
 * Fixed an issue where `CustomItemSerializer` was incorrectly applied to internal SDK query pipeline structures (e.g., `OrderByRowResult`, `Document`), causing deserialization failures in ORDER BY, GROUP BY, aggregate, DISTINCT, and hybrid search queries. - See [PR 48811](https://github.com/Azure/azure-sdk-for-java/pull/48811)
 * Fixed an issue where `SqlParameter` ignored the configured `CustomItemSerializer`, always using the internal default serializer instead. - See [PR 48811](https://github.com/Azure/azure-sdk-for-java/pull/48811)
+* Fixed `NullPointerException` during `ClientTelemetry` static initialization when IMDS access is disabled (`COSMOS_DISABLE_IMDS_ACCESS=true`), which made every `CosmosAsyncClient` build fail with `NoClassDefFoundError`. - See [PR 48887](https://github.com/Azure/azure-sdk-for-java/pull/48887)
 
 #### Other Changes
 
diff --git a/sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/clienttelemetry/ClientTelemetry.java b/sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/clienttelemetry/ClientTelemetry.java
index f5f4f5797689..f25602529c7c 100644
--- a/sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/clienttelemetry/ClientTelemetry.java
+++ b/sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/clienttelemetry/ClientTelemetry.java
@@ -47,15 +47,18 @@ private static ImplementationBridgeHelpers.CosmosClientTelemetryConfigHelper.Cos
     private static final Logger logger = LoggerFactory.getLogger(ClientTelemetry.class);
     private static final String USER_AGENT = Utils.getUserAgent();
 
+    // Sentinel for "not on Azure VM" or "IMDS unreachable".
+    // Must be declared before CACHED_METADATA so that fetchAzureVmMetadata()
+    // never reads a null value during class initialization (e.g. when IMDS
+    // access is disabled via COSMOS_DISABLE_IMDS_ACCESS).
+    private static final AzureVMMetadata METADATA_NOT_AVAILABLE = new AzureVMMetadata();
+
     // Cached IMDS metadata Mono. Reactor's cache() ensures:
     // - The fetch executes at most once
     // - All concurrent subscribers share the single result
     // - The HTTP client is created and disposed within the fetch
     private static final Mono<AzureVMMetadata> CACHED_METADATA = fetchAzureVmMetadata().cache();
 
-    // Sentinel for "not on Azure VM" or "IMDS unreachable"
-    private static final AzureVMMetadata METADATA_NOT_AVAILABLE = new AzureVMMetadata();
-
     // IMDS Constants
     private static final String IMDS_AZURE_VM_METADATA = "http://169.254.169.254:80/metadata/instance?api-version=2020-06-01";
     private static final Duration IMDS_DEFAULT_NETWORK_REQUEST_TIMEOUT = Duration.ofSeconds(5);