diff --git a/CHANGELOG.md b/CHANGELOG.md
index 08dae702cea70..089ba75abf28a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ### Changed
 
+- Lower down the log level to DEBUG ([#18173](https://github.com/opensearch-project/OpenSearch/pull/18173))
+
 ### Dependencies
 - Bump `com.google.code.gson:gson` from 2.12.1 to 2.13.0 ([#17923](https://github.com/opensearch-project/OpenSearch/pull/17923))
 - Bump `com.github.spotbugs:spotbugs-annotations` from 4.9.0 to 4.9.3 ([#17922](https://github.com/opensearch-project/OpenSearch/pull/17922))
diff --git a/server/src/main/java/org/opensearch/cluster/routing/allocation/AllocationService.java b/server/src/main/java/org/opensearch/cluster/routing/allocation/AllocationService.java
index efe51e36ec748..a47f5ddac3f01 100644
--- a/server/src/main/java/org/opensearch/cluster/routing/allocation/AllocationService.java
+++ b/server/src/main/java/org/opensearch/cluster/routing/allocation/AllocationService.java
@@ -625,7 +625,7 @@ private void allocateExistingUnassignedShards(RoutingAllocation allocation) {
             allocateAllUnassignedShards(allocation);
             return;
         }
-        logger.warn("Falling back to single shard assignment since batch mode disable or multiple custom allocators set");
+        logger.debug("Falling back to single shard assignment since batch mode disable or multiple custom allocators set");
 
         final RoutingNodes.UnassignedShards.UnassignedIterator primaryIterator = allocation.routingNodes().unassigned().iterator();
         while (primaryIterator.hasNext()) {