diff --git a/common/unsafe/src/main/java/org/apache/spark/sql/catalyst/util/CollationSupport.java b/common/unsafe/src/main/java/org/apache/spark/sql/catalyst/util/CollationSupport.java
index 5eebec7f1301..a5bb1fe715bb 100644
--- a/common/unsafe/src/main/java/org/apache/spark/sql/catalyst/util/CollationSupport.java
+++ b/common/unsafe/src/main/java/org/apache/spark/sql/catalyst/util/CollationSupport.java
@@ -206,21 +206,22 @@ public static boolean execICU(final UTF8String l, final UTF8String r,
   }
 
   public static class Upper {
-    public static UTF8String exec(final UTF8String v, final int collationId) {
+    public static UTF8String exec(final UTF8String v, final int collationId, boolean useICU) {
       CollationFactory.Collation collation = CollationFactory.fetchCollation(collationId);
       if (collation.supportsBinaryEquality) {
-        return execBinary(v);
+        return useICU ? execBinaryICU(v) : execBinary(v);
       } else if (collation.supportsLowercaseEquality) {
         return execLowercase(v);
       }  else {
         return execICU(v, collationId);
       }
     }
-    public static String genCode(final String v, final int collationId) {
+    public static String genCode(final String v, final int collationId, boolean useICU) {
       CollationFactory.Collation collation = CollationFactory.fetchCollation(collationId);
       String expr = "CollationSupport.Upper.exec";
       if (collation.supportsBinaryEquality) {
-        return String.format(expr + "Binary(%s)", v);
+        String funcName = useICU ? "BinaryICU" : "Binary";
+        return String.format(expr + "%s(%s)", funcName, v);
       } else if (collation.supportsLowercaseEquality) {
         return String.format(expr + "Lowercase(%s)", v);
       }  else {
@@ -230,6 +231,9 @@ public static String genCode(final String v, final int collationId) {
     public static UTF8String execBinary(final UTF8String v) {
       return v.toUpperCase();
     }
+    public static UTF8String execBinaryICU(final UTF8String v) {
+      return CollationAwareUTF8String.toUpperCase(v);
+    }
     public static UTF8String execLowercase(final UTF8String v) {
       return CollationAwareUTF8String.toUpperCase(v);
     }
@@ -239,21 +243,22 @@ public static UTF8String execICU(final UTF8String v, final int collationId) {
   }
 
   public static class Lower {
-    public static UTF8String exec(final UTF8String v, final int collationId) {
+    public static UTF8String exec(final UTF8String v, final int collationId, boolean useICU) {
       CollationFactory.Collation collation = CollationFactory.fetchCollation(collationId);
       if (collation.supportsBinaryEquality) {
-        return execBinary(v);
+        return useICU ? execBinaryICU(v) : execBinary(v);
       } else if (collation.supportsLowercaseEquality) {
         return execLowercase(v);
       } else {
         return execICU(v, collationId);
       }
     }
-    public static String genCode(final String v, final int collationId) {
+    public static String genCode(final String v, final int collationId, boolean useICU) {
       CollationFactory.Collation collation = CollationFactory.fetchCollation(collationId);
-        String expr = "CollationSupport.Lower.exec";
+      String expr = "CollationSupport.Lower.exec";
       if (collation.supportsBinaryEquality) {
-        return String.format(expr + "Binary(%s)", v);
+        String funcName = useICU ? "BinaryICU" : "Binary";
+        return String.format(expr + "%s(%s)", funcName, v);
       } else if (collation.supportsLowercaseEquality) {
         return String.format(expr + "Lowercase(%s)", v);
       }  else {
@@ -263,6 +268,9 @@ public static String genCode(final String v, final int collationId) {
     public static UTF8String execBinary(final UTF8String v) {
       return v.toLowerCase();
     }
+    public static UTF8String execBinaryICU(final UTF8String v) {
+      return CollationAwareUTF8String.toLowerCase(v);
+    }
     public static UTF8String execLowercase(final UTF8String v) {
       return CollationAwareUTF8String.toLowerCase(v);
     }
diff --git a/common/unsafe/src/test/java/org/apache/spark/unsafe/types/CollationSupportSuite.java b/common/unsafe/src/test/java/org/apache/spark/unsafe/types/CollationSupportSuite.java
index 58826005fc46..99f35ef81dc6 100644
--- a/common/unsafe/src/test/java/org/apache/spark/unsafe/types/CollationSupportSuite.java
+++ b/common/unsafe/src/test/java/org/apache/spark/unsafe/types/CollationSupportSuite.java
@@ -606,7 +606,11 @@ private void assertUpper(String target, String collationName, String expected)
     UTF8String target_utf8 = UTF8String.fromString(target);
     UTF8String expected_utf8 = UTF8String.fromString(expected);
     int collationId = CollationFactory.collationNameToId(collationName);
-    assertEquals(expected_utf8, CollationSupport.Upper.exec(target_utf8, collationId));
+    // Testing the new ICU-based implementation of the Upper function.
+    assertEquals(expected_utf8, CollationSupport.Upper.exec(target_utf8, collationId, true));
+    // Testing the old JVM-based implementation of the Upper function.
+    assertEquals(expected_utf8, CollationSupport.Upper.exec(target_utf8, collationId, false));
+    // Note: results should be the same in these tests for both ICU and JVM-based implementations.
   }
 
   @Test
@@ -660,7 +664,11 @@ private void assertLower(String target, String collationName, String expected)
     UTF8String target_utf8 = UTF8String.fromString(target);
     UTF8String expected_utf8 = UTF8String.fromString(expected);
     int collationId = CollationFactory.collationNameToId(collationName);
-    assertEquals(expected_utf8, CollationSupport.Lower.exec(target_utf8, collationId));
+    // Testing the new ICU-based implementation of the Lower function.
+    assertEquals(expected_utf8, CollationSupport.Lower.exec(target_utf8, collationId, true));
+    // Testing the old JVM-based implementation of the Lower function.
+    assertEquals(expected_utf8, CollationSupport.Lower.exec(target_utf8, collationId, false));
+    // Note: results should be the same in these tests for both ICU and JVM-based implementations.
   }
 
   @Test
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringExpressions.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringExpressions.scala
index ac23962f41ed..e0a9d6f77edd 100755
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringExpressions.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringExpressions.scala
@@ -455,12 +455,16 @@ case class Upper(child: Expression)
 
   final lazy val collationId: Int = child.dataType.asInstanceOf[StringType].collationId
 
-  override def convert(v: UTF8String): UTF8String = CollationSupport.Upper.exec(v, collationId)
+  // Flag to indicate whether to use ICU instead of JVM case mappings for UTF8_BINARY collation.
+  private final lazy val useICU = SQLConf.get.getConf(SQLConf.ICU_CASE_MAPPINGS_ENABLED)
+
+  override def convert(v: UTF8String): UTF8String =
+    CollationSupport.Upper.exec(v, collationId, useICU)
 
   final override val nodePatterns: Seq[TreePattern] = Seq(UPPER_OR_LOWER)
 
   override def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
-    defineCodeGen(ctx, ev, c => CollationSupport.Upper.genCode(c, collationId))
+    defineCodeGen(ctx, ev, c => CollationSupport.Upper.genCode(c, collationId, useICU))
   }
 
   override protected def withNewChildInternal(newChild: Expression): Upper = copy(child = newChild)
@@ -483,12 +487,16 @@ case class Lower(child: Expression)
 
   final lazy val collationId: Int = child.dataType.asInstanceOf[StringType].collationId
 
-  override def convert(v: UTF8String): UTF8String = CollationSupport.Lower.exec(v, collationId)
+  // Flag to indicate whether to use ICU instead of JVM case mappings for UTF8_BINARY collation.
+  private final lazy val useICU = SQLConf.get.getConf(SQLConf.ICU_CASE_MAPPINGS_ENABLED)
+
+  override def convert(v: UTF8String): UTF8String =
+    CollationSupport.Lower.exec(v, collationId, useICU)
 
   final override val nodePatterns: Seq[TreePattern] = Seq(UPPER_OR_LOWER)
 
   override def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
-    defineCodeGen(ctx, ev, c => CollationSupport.Lower.genCode(c, collationId))
+    defineCodeGen(ctx, ev, c => CollationSupport.Lower.genCode(c, collationId, useICU))
   }
 
   override def prettyName: String =
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 fd804bc0e986..799e54aaecea 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
@@ -785,6 +785,14 @@ object SQLConf {
         _ => Map())
       .createWithDefault("UTF8_BINARY")
 
+  val ICU_CASE_MAPPINGS_ENABLED =
+    buildConf("spark.sql.icu.caseMappings.enabled")
+      .doc("When enabled we use the ICU library (instead of the JVM) to implement case mappings" +
+        " for strings under UTF8_BINARY collation.")
+      .version("4.0.0")
+      .booleanConf
+      .createWithDefault(true)
+
   val FETCH_SHUFFLE_BLOCKS_IN_BATCH =
     buildConf("spark.sql.adaptive.fetchShuffleBlocksInBatch")
       .internal()