diff --git a/.changelog/42541.txt b/.changelog/42541.txt
new file mode 100644
index 000000000000..7f878c8393e7
--- /dev/null
+++ b/.changelog/42541.txt
@@ -0,0 +1,3 @@
+```release-note:bug
+resource/aws_rds_cluster: Fixes the behavior when enabling database_insights_mode="advanced" without changing performance insights retention window
+```
\ No newline at end of file
diff --git a/internal/service/rds/cluster.go b/internal/service/rds/cluster.go
index d69681362bd6..4914e066dcb7 100644
--- a/internal/service/rds/cluster.go
+++ b/internal/service/rds/cluster.go
@@ -1615,6 +1615,7 @@ func resourceClusterUpdate(ctx context.Context, d *schema.ResourceData, meta any
 		if d.HasChange("database_insights_mode") {
 			input.DatabaseInsightsMode = types.DatabaseInsightsMode(d.Get("database_insights_mode").(string))
 			input.EnablePerformanceInsights = aws.Bool(d.Get("performance_insights_enabled").(bool))
+			input.PerformanceInsightsRetentionPeriod = aws.Int32(int32(d.Get("performance_insights_retention_period").(int)))
 		}
 
 		if d.HasChange("db_cluster_instance_class") {