diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala
index 983285ceb2ee..fda37dbe0a03 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala
@@ -2850,6 +2850,7 @@ object SQLConf {
       .createWithDefault(100)
 
   val LEGACY_ALLOW_HASH_ON_MAPTYPE = buildConf("spark.sql.legacy.allowHashOnMapType")
+    .internal()
     .doc("When set to true, hash expressions can be applied on elements of MapType. Otherwise, " +
       "an analysis exception will be thrown.")
     .version("3.0.0")
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/internal/StaticSQLConf.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/internal/StaticSQLConf.scala
index 02cb6f29622f..bfefca4e2eba 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/internal/StaticSQLConf.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/internal/StaticSQLConf.scala
@@ -195,6 +195,7 @@ object StaticSQLConf {
 
   val SQL_LEGACY_SESSION_INIT_WITH_DEFAULTS =
     buildStaticConf("spark.sql.legacy.sessionInitWithConfigDefaults")
+      .internal()
       .doc("Flag to revert to legacy behavior where a cloned SparkSession receives SparkConf " +
         "defaults, dropping any overrides in its parent SparkSession.")
       .version("3.0.0")
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/internal/SQLConfSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/internal/SQLConfSuite.scala
index e699c972268a..93b785952768 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/internal/SQLConfSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/internal/SQLConfSuite.scala
@@ -451,4 +451,14 @@ class SQLConfSuite extends QueryTest with SharedSparkSession {
     val e2 = intercept[ParseException](sql("set time zone interval 19 hours"))
     assert(e2.getMessage contains "The interval value must be in the range of [-18, +18] hours")
   }
+
+  test("SPARK-34454: configs from the legacy namespace should be internal") {
+    val nonInternalLegacyConfigs = spark.sessionState.conf.getAllDefinedConfs
+      .filter { case (key, _, _, _) => key.contains("spark.sql.legacy.") }
+    assert(nonInternalLegacyConfigs.isEmpty,
+      s"""
+         |Non internal legacy SQL configs:
+         |${nonInternalLegacyConfigs.map(_._1).mkString("\n")}
+         |""".stripMargin)
+  }
 }