diff --git a/hudi-spark-datasource/hudi-spark-common/src/main/scala/org/apache/hudi/HoodieSparkSqlWriter.scala b/hudi-spark-datasource/hudi-spark-common/src/main/scala/org/apache/hudi/HoodieSparkSqlWriter.scala
index aaa79929256f6..d6f2baf28d677 100644
--- a/hudi-spark-datasource/hudi-spark-common/src/main/scala/org/apache/hudi/HoodieSparkSqlWriter.scala
+++ b/hudi-spark-datasource/hudi-spark-common/src/main/scala/org/apache/hudi/HoodieSparkSqlWriter.scala
@@ -1125,6 +1125,17 @@ class HoodieSparkSqlWriterInternal {
       mergedParams.put(HoodieTableConfig.DROP_PARTITION_COLUMNS.key, "false")
     }
 
+    // Lance is Spark-only and its writer/reader only handles Spark InternalRow, not Avro.
+    // Auto-set DefaultSparkRecordMerger when the user hasn't explicitly configured a merger.
+    if (HoodieFileFormat.LANCE.name().equalsIgnoreCase(
+          mergedParams.getOrElse(HoodieTableConfig.BASE_FILE_FORMAT.key(),
+            HoodieTableConfig.BASE_FILE_FORMAT.defaultValue().name()))
+        && !optParams.contains(HoodieWriteConfig.RECORD_MERGE_IMPL_CLASSES.key())
+        && !optParams.contains(HoodieReaderConfig.RECORD_MERGE_IMPL_CLASSES_DEPRECATED_WRITE_CONFIG_KEY)) {
+      mergedParams.put(HoodieWriteConfig.RECORD_MERGE_IMPL_CLASSES.key(),
+        classOf[DefaultSparkRecordMerger].getName)
+    }
+
     val tableVersion = if (tableConfig != null) {
       tableConfig.getTableVersion
     } else {
diff --git a/hudi-spark-datasource/hudi-spark/src/test/scala/org/apache/hudi/common/table/read/TestHoodieFileGroupReaderOnSpark.scala b/hudi-spark-datasource/hudi-spark/src/test/scala/org/apache/hudi/common/table/read/TestHoodieFileGroupReaderOnSpark.scala
index d4eae9e79d74d..fab9f5d855513 100644
--- a/hudi-spark-datasource/hudi-spark/src/test/scala/org/apache/hudi/common/table/read/TestHoodieFileGroupReaderOnSpark.scala
+++ b/hudi-spark-datasource/hudi-spark/src/test/scala/org/apache/hudi/common/table/read/TestHoodieFileGroupReaderOnSpark.scala
@@ -19,7 +19,7 @@
 
 package org.apache.hudi.common.table.read
 
-import org.apache.hudi.{AvroConversionUtils, DataSourceWriteOptions, DefaultSparkRecordMerger, HoodieSchemaConversionUtils, HoodieSparkUtils, SparkAdapterSupport, SparkFileFormatInternalRowReaderContext}
+import org.apache.hudi.{AvroConversionUtils, DataSourceWriteOptions, HoodieSchemaConversionUtils, HoodieSparkUtils, SparkAdapterSupport, SparkFileFormatInternalRowReaderContext}
 import org.apache.hudi.DataSourceWriteOptions.{OPERATION, RECORDKEY_FIELD, TABLE_TYPE}
 import org.apache.hudi.common.config.{HoodieReaderConfig, RecordMergeMode, TypedProperties}
 import org.apache.hudi.common.engine.HoodieReaderContext
@@ -132,19 +132,12 @@ class TestHoodieFileGroupReaderOnSpark extends TestHoodieFileGroupReaderBase[Int
     val inputDF: Dataset[Row] = AvroConversionUtils.createDataFrame(genericRecords, schemaStr, spark);
 
     // Check if Lance format is being used and add required configuration
-    val isLanceFormat = options.getOrDefault(HoodieTableConfig.BASE_FILE_FORMAT.key(), "").equalsIgnoreCase("LANCE")
-
     var writer = inputDF.write.format("hudi")
       .options(options)
       .option("hoodie.compact.inline", "false") // else fails due to compaction & deltacommit instant times being same
       .option("hoodie.datasource.write.operation", operation)
       .option("hoodie.datasource.write.table.type", "MERGE_ON_READ")
 
-    // Lance requires DefaultSparkRecordMerger for Spark InternalRow compatibility
-    if (isLanceFormat) {
-      writer = writer.option(HoodieWriteConfig.RECORD_MERGE_IMPL_CLASSES.key(), classOf[DefaultSparkRecordMerger].getName)
-    }
-
     writer.mode(if (firstCommit) SaveMode.Overwrite else SaveMode.Append)
       .save(getBasePath)
   }
diff --git a/hudi-spark-datasource/hudi-spark/src/test/scala/org/apache/hudi/functional/TestLanceDataSource.scala b/hudi-spark-datasource/hudi-spark/src/test/scala/org/apache/hudi/functional/TestLanceDataSource.scala
index 1cd5647d99495..3de7aa7061dfb 100644
--- a/hudi-spark-datasource/hudi-spark/src/test/scala/org/apache/hudi/functional/TestLanceDataSource.scala
+++ b/hudi-spark-datasource/hudi-spark/src/test/scala/org/apache/hudi/functional/TestLanceDataSource.scala
@@ -18,7 +18,6 @@
 package org.apache.hudi.functional
 
 import org.apache.hudi.DataSourceWriteOptions._
-import org.apache.hudi.DefaultSparkRecordMerger
 import org.apache.hudi.blob.BlobTestHelpers
 import org.apache.hudi.common.config.{HoodieCommonConfig, HoodieMetadataConfig}
 import org.apache.hudi.common.engine.HoodieLocalEngineContext
@@ -1103,7 +1102,6 @@ class TestLanceDataSource extends HoodieSparkClientTestBase {
     val createTablePartitionClause = if (isPartitioned) "partitioned by (dt)" else ""
 
     // CREATE TABLE with Lance configuration
-    // Lance format requires Spark record merger for writing
     spark.sql(s"""
       create table $tableName (
         id int,
@@ -1115,8 +1113,7 @@ class TestLanceDataSource extends HoodieSparkClientTestBase {
       tblproperties (
         hoodie.table.base.file.format = 'LANCE',
         type = '${tableType.name()}',
-        primaryKey = 'id',
-        hoodie.datasource.write.record.merger.impls = '${classOf[DefaultSparkRecordMerger].getName}'
+        primaryKey = 'id'
       )
       $createTablePartitionClause
       location '$tablePath'
@@ -1488,7 +1485,6 @@ class TestLanceDataSource extends HoodieSparkClientTestBase {
       .option(PRECOMBINE_FIELD.key(), "age")
       .option(TABLE_NAME.key(), tableName)
       .option(HoodieWriteConfig.TBL_NAME.key(), tableName)
-      .option(HoodieWriteConfig.RECORD_MERGE_IMPL_CLASSES.key(), classOf[DefaultSparkRecordMerger].getName)
 
     // Add operation if specified
     writer = operation match {