diff --git a/flink-connector-kafka/src/main/java/org/apache/flink/connector/kafka/sink/KafkaSerializerWrapper.java b/flink-connector-kafka/src/main/java/org/apache/flink/connector/kafka/sink/KafkaSerializerWrapper.java
index f2120568b..6bc811a46 100644
--- a/flink-connector-kafka/src/main/java/org/apache/flink/connector/kafka/sink/KafkaSerializerWrapper.java
+++ b/flink-connector-kafka/src/main/java/org/apache/flink/connector/kafka/sink/KafkaSerializerWrapper.java
@@ -61,17 +61,12 @@ class KafkaSerializerWrapper<IN> implements SerializationSchema<IN> {
         this(serializerClass, isKey, Collections.emptyMap(), topicSelector);
     }
 
-    @SuppressWarnings("unchecked")
     @Override
     public void open(InitializationContext context) throws Exception {
         final ClassLoader userCodeClassLoader = context.getUserCodeClassLoader().asClassLoader();
         try (TemporaryClassLoaderContext ignored =
                 TemporaryClassLoaderContext.of(userCodeClassLoader)) {
-            serializer =
-                    InstantiationUtil.instantiate(
-                            serializerClass.getName(),
-                            Serializer.class,
-                            getClass().getClassLoader());
+            initializeSerializer(userCodeClassLoader);
 
             if (serializer instanceof Configurable) {
                 ((Configurable) serializer).configure(config);
@@ -88,4 +83,11 @@ public byte[] serialize(IN element) {
         checkState(serializer != null, "Call open() once before trying to serialize elements.");
         return serializer.serialize(topicSelector.apply(element), element);
     }
+
+    @SuppressWarnings("unchecked")
+    protected void initializeSerializer(ClassLoader classLoader) throws Exception {
+        serializer =
+                InstantiationUtil.instantiate(
+                        serializerClass.getName(), Serializer.class, classLoader);
+    }
 }
diff --git a/flink-connector-kafka/src/main/java/org/apache/flink/connector/kafka/source/reader/deserializer/KafkaValueOnlyDeserializerWrapper.java b/flink-connector-kafka/src/main/java/org/apache/flink/connector/kafka/source/reader/deserializer/KafkaValueOnlyDeserializerWrapper.java
index 8c8095b6b..4d320fcc8 100644
--- a/flink-connector-kafka/src/main/java/org/apache/flink/connector/kafka/source/reader/deserializer/KafkaValueOnlyDeserializerWrapper.java
+++ b/flink-connector-kafka/src/main/java/org/apache/flink/connector/kafka/source/reader/deserializer/KafkaValueOnlyDeserializerWrapper.java
@@ -55,17 +55,11 @@ class KafkaValueOnlyDeserializerWrapper<T> implements KafkaRecordDeserialization
     }
 
     @Override
-    @SuppressWarnings("unchecked")
     public void open(DeserializationSchema.InitializationContext context) throws Exception {
         ClassLoader userCodeClassLoader = context.getUserCodeClassLoader().asClassLoader();
         try (TemporaryClassLoaderContext ignored =
                 TemporaryClassLoaderContext.of(userCodeClassLoader)) {
-            deserializer =
-                    (Deserializer<T>)
-                            InstantiationUtil.instantiate(
-                                    deserializerClass.getName(),
-                                    Deserializer.class,
-                                    getClass().getClassLoader());
+            initializeDeserializer(userCodeClassLoader);
 
             if (deserializer instanceof Configurable) {
                 ((Configurable) deserializer).configure(config);
@@ -103,4 +97,11 @@ public void deserialize(ConsumerRecord<byte[], byte[]> record, Collector<T> coll
     public TypeInformation<T> getProducedType() {
         return TypeExtractor.createTypeInfo(Deserializer.class, deserializerClass, 0, null, null);
     }
+
+    @SuppressWarnings("unchecked")
+    protected void initializeDeserializer(ClassLoader classLoader) throws Exception {
+        deserializer =
+                InstantiationUtil.instantiate(
+                        deserializerClass.getName(), Deserializer.class, classLoader);
+    }
 }
diff --git a/flink-connector-kafka/src/test/java/org/apache/flink/connector/kafka/sink/KafkaSerializerWrapperTest.java b/flink-connector-kafka/src/test/java/org/apache/flink/connector/kafka/sink/KafkaSerializerWrapperTest.java
new file mode 100644
index 000000000..2f8d872a8
--- /dev/null
+++ b/flink-connector-kafka/src/test/java/org/apache/flink/connector/kafka/sink/KafkaSerializerWrapperTest.java
@@ -0,0 +1,74 @@
+package org.apache.flink.connector.kafka.sink;
+
+import org.apache.flink.api.common.serialization.SerializationSchema;
+import org.apache.flink.connector.testutils.formats.DummyInitializationContext;
+import org.apache.flink.metrics.MetricGroup;
+import org.apache.flink.metrics.groups.UnregisteredMetricsGroup;
+import org.apache.flink.util.FlinkUserCodeClassLoaders;
+import org.apache.flink.util.SimpleUserCodeClassLoader;
+import org.apache.flink.util.UserCodeClassLoader;
+
+import org.apache.kafka.common.serialization.StringSerializer;
+import org.junit.Test;
+
+import java.net.URL;
+
+import static org.junit.Assert.assertEquals;
+
+/** Tests for {@link KafkaSerializerWrapper}. */
+public class KafkaSerializerWrapperTest {
+    @Test
+    public void testUserCodeClassLoaderIsUsed() throws Exception {
+        final KafkaSerializerWrapperCaptureForTest wrapper =
+                new KafkaSerializerWrapperCaptureForTest();
+        final ClassLoader classLoader =
+                FlinkUserCodeClassLoaders.childFirst(
+                        new URL[0],
+                        getClass().getClassLoader(),
+                        new String[0],
+                        throwable -> {},
+                        true);
+        wrapper.open(
+                new SerializationSchema.InitializationContext() {
+                    @Override
+                    public MetricGroup getMetricGroup() {
+                        return new UnregisteredMetricsGroup();
+                    }
+
+                    @Override
+                    public UserCodeClassLoader getUserCodeClassLoader() {
+                        return SimpleUserCodeClassLoader.create(classLoader);
+                    }
+                });
+
+        assertEquals(classLoader, wrapper.getClassLoaderUsed());
+    }
+
+    @Test
+    public void testDefaultClassLoaderIsUsed() throws Exception {
+        final KafkaSerializerWrapperCaptureForTest wrapper =
+                new KafkaSerializerWrapperCaptureForTest();
+        wrapper.open(new DummyInitializationContext());
+
+        assertEquals(
+                DummyInitializationContext.class.getClassLoader(), wrapper.getClassLoaderUsed());
+    }
+
+    static class KafkaSerializerWrapperCaptureForTest extends KafkaSerializerWrapper<String> {
+        private ClassLoader classLoaderUsed;
+
+        KafkaSerializerWrapperCaptureForTest() {
+            super(StringSerializer.class, true, (value) -> "topic");
+        }
+
+        public ClassLoader getClassLoaderUsed() {
+            return classLoaderUsed;
+        }
+
+        @Override
+        protected void initializeSerializer(ClassLoader classLoader) throws Exception {
+            classLoaderUsed = classLoader;
+            super.initializeSerializer(classLoader);
+        }
+    }
+}
diff --git a/flink-connector-kafka/src/test/java/org/apache/flink/connector/kafka/source/reader/deserializer/KafkaValueOnlyDeserializerWrapperTest.java b/flink-connector-kafka/src/test/java/org/apache/flink/connector/kafka/source/reader/deserializer/KafkaValueOnlyDeserializerWrapperTest.java
new file mode 100644
index 000000000..312bfbcdf
--- /dev/null
+++ b/flink-connector-kafka/src/test/java/org/apache/flink/connector/kafka/source/reader/deserializer/KafkaValueOnlyDeserializerWrapperTest.java
@@ -0,0 +1,76 @@
+package org.apache.flink.connector.kafka.source.reader.deserializer;
+
+import org.apache.flink.api.common.serialization.DeserializationSchema;
+import org.apache.flink.connector.testutils.formats.DummyInitializationContext;
+import org.apache.flink.metrics.MetricGroup;
+import org.apache.flink.metrics.groups.UnregisteredMetricsGroup;
+import org.apache.flink.util.FlinkUserCodeClassLoaders;
+import org.apache.flink.util.SimpleUserCodeClassLoader;
+import org.apache.flink.util.UserCodeClassLoader;
+
+import org.apache.kafka.common.serialization.StringDeserializer;
+import org.junit.Test;
+
+import java.net.URL;
+import java.util.HashMap;
+
+import static org.junit.Assert.assertEquals;
+
+/** Tests for {@link KafkaValueOnlyDeserializerWrapper}. */
+public class KafkaValueOnlyDeserializerWrapperTest {
+    @Test
+    public void testUserCodeClassLoaderIsUsed() throws Exception {
+        final KafkaValueOnlyDeserializerWrapperCaptureForTest wrapper =
+                new KafkaValueOnlyDeserializerWrapperCaptureForTest();
+        final ClassLoader classLoader =
+                FlinkUserCodeClassLoaders.childFirst(
+                        new URL[0],
+                        getClass().getClassLoader(),
+                        new String[0],
+                        throwable -> {},
+                        true);
+        wrapper.open(
+                new DeserializationSchema.InitializationContext() {
+                    @Override
+                    public MetricGroup getMetricGroup() {
+                        return new UnregisteredMetricsGroup();
+                    }
+
+                    @Override
+                    public UserCodeClassLoader getUserCodeClassLoader() {
+                        return SimpleUserCodeClassLoader.create(classLoader);
+                    }
+                });
+
+        assertEquals(classLoader, wrapper.getClassLoaderUsed());
+    }
+
+    @Test
+    public void testDefaultClassLoaderIsUsed() throws Exception {
+        final KafkaValueOnlyDeserializerWrapperCaptureForTest wrapper =
+                new KafkaValueOnlyDeserializerWrapperCaptureForTest();
+        wrapper.open(new DummyInitializationContext());
+
+        assertEquals(
+                DummyInitializationContext.class.getClassLoader(), wrapper.getClassLoaderUsed());
+    }
+
+    static class KafkaValueOnlyDeserializerWrapperCaptureForTest
+            extends KafkaValueOnlyDeserializerWrapper<String> {
+        private ClassLoader classLoaderUsed;
+
+        KafkaValueOnlyDeserializerWrapperCaptureForTest() {
+            super(StringDeserializer.class, new HashMap<>());
+        }
+
+        public ClassLoader getClassLoaderUsed() {
+            return classLoaderUsed;
+        }
+
+        @Override
+        protected void initializeDeserializer(ClassLoader classLoader) throws Exception {
+            classLoaderUsed = classLoader;
+            super.initializeDeserializer(classLoader);
+        }
+    }
+}