diff --git a/docs/source/user-guide/latest/in-memory-cache.md b/docs/source/user-guide/latest/in-memory-cache.md
index c37fa2dc32..75ae617d6e 100644
--- a/docs/source/user-guide/latest/in-memory-cache.md
+++ b/docs/source/user-guide/latest/in-memory-cache.md
@@ -24,13 +24,13 @@ format that Comet operators read directly. Without it, a cached table is stored
 format and every scan of it has to convert each batch before Comet can continue, which shows up in
 the plan as a `CometSparkColumnarToColumnar` above the cache scan.
 
-This feature is **experimental and disabled by default**. Turn it on at startup, alongside the rest
-of Comet's configuration:
+This feature is **experimental and enabled by default**. To turn it off, set the config at startup,
+alongside the rest of Comet's configuration:
 
 ```shell
 $SPARK_HOME/bin/spark-shell \
     ... \
-    --conf spark.comet.exec.inMemoryCache.enabled=true
+    --conf spark.comet.exec.inMemoryCache.enabled=false
 ```
 
 It has to be set before the `SparkContext` starts. Comet's driver plugin chooses
@@ -99,7 +99,7 @@ nowhere to record either that a column is dictionary encoded or the dictionary i
 
 | Config                                                  | Default | Description                                                                                                                                    |
 | ------------------------------------------------------- | ------- | ---------------------------------------------------------------------------------------------------------------------------------------------- |
-| `spark.comet.exec.inMemoryCache.enabled`                | `false` | Whether to store and scan Spark's in-memory cache in Comet's format. Read at startup.                                                          |
+| `spark.comet.exec.inMemoryCache.enabled`                | `true`  | Whether to store and scan Spark's in-memory cache in Comet's format. Read at startup.                                                          |
 | `spark.comet.exec.inMemoryCache.compression.codec`      | `zstd`  | Arrow IPC compression codec for cached data: `zstd` or `none`. Affects newly cached data only — a batch records the codec it was written with. |
 | `spark.comet.exec.inMemoryCache.compression.zstd.level` | `1`     | Compression level when the codec is `zstd`. Ignored otherwise.                                                                                 |
 
@@ -186,8 +186,8 @@ format, and the narrower the read, the wider the gap. Measured by the same bench
 | 3 of 6 columns          |                98 ms |               331 ms |     3.4x |
 | 6 of 6 columns          |               410 ms |               623 ms |     1.5x |
 
-This is why the feature is off by default. The cause is not yet established;
-[#5485](https://github.com/apache/datafusion-comet/issues/5485) tracks it.
+This is the main reason the feature is still described as experimental. The cause is not yet
+established; [#5485](https://github.com/apache/datafusion-comet/issues/5485) tracks it.
 
 Comet's serializer exists because Spark's own Arrow cache format
 ([SPARK-57268](https://issues.apache.org/jira/browse/SPARK-57268)) is only available from Spark
diff --git a/spark/src/main/scala/org/apache/comet/CometConf.scala b/spark/src/main/scala/org/apache/comet/CometConf.scala
index 9ee128e46f..4d391944c1 100644
--- a/spark/src/main/scala/org/apache/comet/CometConf.scala
+++ b/spark/src/main/scala/org/apache/comet/CometConf.scala
@@ -278,7 +278,7 @@ object CometConf extends ShimCometConf {
         "SparkContext, otherwise caching fails as soon as a block is serialized, including " +
         "the disk half of the default MEMORY_AND_DISK storage level.")
       .booleanConf
-      .createWithDefault(false)
+      .createWithDefault(true)
 
   val COMET_EXEC_IN_MEMORY_CACHE_COMPRESSION_CODEC: ConfigEntry[String] =
     conf("spark.comet.exec.inMemoryCache.compression.codec")
diff --git a/spark/src/main/scala/org/apache/spark/Plugins.scala b/spark/src/main/scala/org/apache/spark/Plugins.scala
index d040208596..567178981d 100644
--- a/spark/src/main/scala/org/apache/spark/Plugins.scala
+++ b/spark/src/main/scala/org/apache/spark/Plugins.scala
@@ -104,7 +104,9 @@ object CometDriverPlugin extends Logging {
   private[apache] def maybeSetCacheSerializer(
       conf: SparkConf,
       extraConfs: ju.HashMap[String, String]): Unit = {
-    if (conf.getBoolean(CometConf.COMET_EXEC_IN_MEMORY_CACHE_ENABLED.key, false)) {
+    if (conf.getBoolean(
+        CometConf.COMET_EXEC_IN_MEMORY_CACHE_ENABLED.key,
+        CometConf.COMET_EXEC_IN_MEMORY_CACHE_ENABLED.defaultValue.get)) {
       val serializerKey = StaticSQLConf.SPARK_CACHE_SERIALIZER.key
       val serializerValue =
         "org.apache.spark.sql.comet.execution.arrow.ArrowCachedBatchSerializer"