diff --git a/core/src/main/java/org/apache/iceberg/avro/ValueWriters.java b/core/src/main/java/org/apache/iceberg/avro/ValueWriters.java
index b99b67fe7f4b..1658db96c21a 100644
--- a/core/src/main/java/org/apache/iceberg/avro/ValueWriters.java
+++ b/core/src/main/java/org/apache/iceberg/avro/ValueWriters.java
@@ -35,6 +35,7 @@
 import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
 import org.apache.iceberg.types.TypeUtil;
 import org.apache.iceberg.util.DecimalUtil;
+import org.apache.iceberg.util.UUIDUtil;
 
 public class ValueWriters {
   private ValueWriters() {}
@@ -263,12 +264,8 @@ private UUIDWriter() {}
     @Override
     @SuppressWarnings("ByteBufferBackingArray")
     public void write(UUID uuid, Encoder encoder) throws IOException {
-      // TODO: direct conversion from string to byte buffer
-      ByteBuffer buffer = BUFFER.get();
-      buffer.rewind();
-      buffer.putLong(uuid.getMostSignificantBits());
-      buffer.putLong(uuid.getLeastSignificantBits());
-      encoder.writeFixed(buffer.array());
+      // calling array() is safe because the buffer is always allocated by the thread-local
+      encoder.writeFixed(UUIDUtil.convertToByteBuffer(uuid, BUFFER.get()).array());
     }
   }
 
diff --git a/spark/v3.1/spark/src/main/java/org/apache/iceberg/spark/data/SparkValueWriters.java b/spark/v3.1/spark/src/main/java/org/apache/iceberg/spark/data/SparkValueWriters.java
index 5f2e2c054888..bb8218bd83df 100644
--- a/spark/v3.1/spark/src/main/java/org/apache/iceberg/spark/data/SparkValueWriters.java
+++ b/spark/v3.1/spark/src/main/java/org/apache/iceberg/spark/data/SparkValueWriters.java
@@ -29,6 +29,7 @@
 import org.apache.iceberg.avro.ValueWriter;
 import org.apache.iceberg.types.TypeUtil;
 import org.apache.iceberg.util.DecimalUtil;
+import org.apache.iceberg.util.UUIDUtil;
 import org.apache.spark.sql.catalyst.InternalRow;
 import org.apache.spark.sql.catalyst.util.ArrayData;
 import org.apache.spark.sql.catalyst.util.MapData;
@@ -102,11 +103,8 @@ private UUIDWriter() {}
     public void write(UTF8String s, Encoder encoder) throws IOException {
       // TODO: direct conversion from string to byte buffer
       UUID uuid = UUID.fromString(s.toString());
-      ByteBuffer buffer = BUFFER.get();
-      buffer.rewind();
-      buffer.putLong(uuid.getMostSignificantBits());
-      buffer.putLong(uuid.getLeastSignificantBits());
-      encoder.writeFixed(buffer.array());
+      // calling array() is safe because the buffer is always allocated by the thread-local
+      encoder.writeFixed(UUIDUtil.convertToByteBuffer(uuid, BUFFER.get()).array());
     }
   }
 
diff --git a/spark/v3.2/spark/src/main/java/org/apache/iceberg/spark/data/SparkValueWriters.java b/spark/v3.2/spark/src/main/java/org/apache/iceberg/spark/data/SparkValueWriters.java
index 5f2e2c054888..bb8218bd83df 100644
--- a/spark/v3.2/spark/src/main/java/org/apache/iceberg/spark/data/SparkValueWriters.java
+++ b/spark/v3.2/spark/src/main/java/org/apache/iceberg/spark/data/SparkValueWriters.java
@@ -29,6 +29,7 @@
 import org.apache.iceberg.avro.ValueWriter;
 import org.apache.iceberg.types.TypeUtil;
 import org.apache.iceberg.util.DecimalUtil;
+import org.apache.iceberg.util.UUIDUtil;
 import org.apache.spark.sql.catalyst.InternalRow;
 import org.apache.spark.sql.catalyst.util.ArrayData;
 import org.apache.spark.sql.catalyst.util.MapData;
@@ -102,11 +103,8 @@ private UUIDWriter() {}
     public void write(UTF8String s, Encoder encoder) throws IOException {
       // TODO: direct conversion from string to byte buffer
       UUID uuid = UUID.fromString(s.toString());
-      ByteBuffer buffer = BUFFER.get();
-      buffer.rewind();
-      buffer.putLong(uuid.getMostSignificantBits());
-      buffer.putLong(uuid.getLeastSignificantBits());
-      encoder.writeFixed(buffer.array());
+      // calling array() is safe because the buffer is always allocated by the thread-local
+      encoder.writeFixed(UUIDUtil.convertToByteBuffer(uuid, BUFFER.get()).array());
     }
   }
 
diff --git a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/data/SparkValueWriters.java b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/data/SparkValueWriters.java
index 5f2e2c054888..bb8218bd83df 100644
--- a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/data/SparkValueWriters.java
+++ b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/data/SparkValueWriters.java
@@ -29,6 +29,7 @@
 import org.apache.iceberg.avro.ValueWriter;
 import org.apache.iceberg.types.TypeUtil;
 import org.apache.iceberg.util.DecimalUtil;
+import org.apache.iceberg.util.UUIDUtil;
 import org.apache.spark.sql.catalyst.InternalRow;
 import org.apache.spark.sql.catalyst.util.ArrayData;
 import org.apache.spark.sql.catalyst.util.MapData;
@@ -102,11 +103,8 @@ private UUIDWriter() {}
     public void write(UTF8String s, Encoder encoder) throws IOException {
       // TODO: direct conversion from string to byte buffer
       UUID uuid = UUID.fromString(s.toString());
-      ByteBuffer buffer = BUFFER.get();
-      buffer.rewind();
-      buffer.putLong(uuid.getMostSignificantBits());
-      buffer.putLong(uuid.getLeastSignificantBits());
-      encoder.writeFixed(buffer.array());
+      // calling array() is safe because the buffer is always allocated by the thread-local
+      encoder.writeFixed(UUIDUtil.convertToByteBuffer(uuid, BUFFER.get()).array());
     }
   }
 
diff --git a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/data/SparkValueWriters.java b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/data/SparkValueWriters.java
index 5f2e2c054888..bb8218bd83df 100644
--- a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/data/SparkValueWriters.java
+++ b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/data/SparkValueWriters.java
@@ -29,6 +29,7 @@
 import org.apache.iceberg.avro.ValueWriter;
 import org.apache.iceberg.types.TypeUtil;
 import org.apache.iceberg.util.DecimalUtil;
+import org.apache.iceberg.util.UUIDUtil;
 import org.apache.spark.sql.catalyst.InternalRow;
 import org.apache.spark.sql.catalyst.util.ArrayData;
 import org.apache.spark.sql.catalyst.util.MapData;
@@ -102,11 +103,8 @@ private UUIDWriter() {}
     public void write(UTF8String s, Encoder encoder) throws IOException {
       // TODO: direct conversion from string to byte buffer
       UUID uuid = UUID.fromString(s.toString());
-      ByteBuffer buffer = BUFFER.get();
-      buffer.rewind();
-      buffer.putLong(uuid.getMostSignificantBits());
-      buffer.putLong(uuid.getLeastSignificantBits());
-      encoder.writeFixed(buffer.array());
+      // calling array() is safe because the buffer is always allocated by the thread-local
+      encoder.writeFixed(UUIDUtil.convertToByteBuffer(uuid, BUFFER.get()).array());
     }
   }