diff --git a/icu4j/main/core/src/main/java/com/ibm/icu/impl/ICUService.java b/icu4j/main/core/src/main/java/com/ibm/icu/impl/ICUService.java
index 2b6981d384c..1eb1a0767f3 100644
--- a/icu4j/main/core/src/main/java/com/ibm/icu/impl/ICUService.java
+++ b/icu4j/main/core/src/main/java/com/ibm/icu/impl/ICUService.java
@@ -592,13 +592,17 @@ public class ICUService extends ICUNotifier {
                         Factory f = lIter.previous();
                         f.updateVisibleIDs(mutableMap);
                     }
-                    this.idcache = Collections.unmodifiableMap(mutableMap);
+                    // Capture the return value in a local variable.
+                    // Avoids returning an idcache value changed by another thread (could be null after clearCaches()).
+                    Map<String, Factory> result = Collections.unmodifiableMap(mutableMap);
+                    this.idcache = result;
+                    return result;
                 } finally {
                     factoryLock.releaseRead();
                 }
             }
+            return idcache;
         }
-        return idcache;
     }
     private Map<String, Factory> idcache;