diff --git a/common/unsafe/src/main/java/org/apache/spark/unsafe/types/ByteArray.java b/common/unsafe/src/main/java/org/apache/spark/unsafe/types/ByteArray.java
index 3ced2094f5..7ced13d357 100644
--- a/common/unsafe/src/main/java/org/apache/spark/unsafe/types/ByteArray.java
+++ b/common/unsafe/src/main/java/org/apache/spark/unsafe/types/ByteArray.java
@@ -44,7 +44,7 @@ public final class ByteArray {
       final int minLen = Math.min(bytes.length, 8);
       long p = 0;
       for (int i = 0; i < minLen; ++i) {
-        p |= (128L + Platform.getByte(bytes, Platform.BYTE_ARRAY_OFFSET + i))
+        p |= ((long) Platform.getByte(bytes, Platform.BYTE_ARRAY_OFFSET + i) & 0xff)
             << (56 - 8 * i);
       }
       return p;
diff --git a/core/src/test/scala/org/apache/spark/util/collection/unsafe/sort/PrefixComparatorsSuite.scala b/core/src/test/scala/org/apache/spark/util/collection/unsafe/sort/PrefixComparatorsSuite.scala
index 5180c58a56..73546ef1b7 100644
--- a/core/src/test/scala/org/apache/spark/util/collection/unsafe/sort/PrefixComparatorsSuite.scala
+++ b/core/src/test/scala/org/apache/spark/util/collection/unsafe/sort/PrefixComparatorsSuite.scala
@@ -63,7 +63,9 @@ class PrefixComparatorsSuite extends SparkFunSuite with PropertyChecks {
 
      def compareBinary(x: Array[Byte], y: Array[Byte]): Int = {
       for (i <- 0 until x.length; if i < y.length) {
-        val res = x(i).compare(y(i))
+        val v1 = x(i) & 0xff
+        val v2 = y(i) & 0xff
+        val res = v1 - v2
         if (res != 0) return res
       }
       x.length - y.length
@@ -80,6 +82,19 @@ class PrefixComparatorsSuite extends SparkFunSuite with PropertyChecks {
         (prefixComparisonResult > 0 && compareBinary(x, y) > 0))
     }
 
+    val binaryRegressionTests = Seq(
+      (Array[Byte](1), Array[Byte](-1)),
+      (Array[Byte](1, 1, 1, 1, 1), Array[Byte](1, 1, 1, 1, -1)),
+      (Array[Byte](1, 1, 1, 1, 1, 1, 1, 1, 1), Array[Byte](1, 1, 1, 1, 1, 1, 1, 1, -1)),
+      (Array[Byte](1), Array[Byte](1, 1, 1, 1)),
+      (Array[Byte](1, 1, 1, 1, 1), Array[Byte](1, 1, 1, 1, 1, 1, 1, 1, 1)),
+      (Array[Byte](-1), Array[Byte](-1, -1, -1, -1)),
+      (Array[Byte](-1, -1, -1, -1, -1), Array[Byte](-1, -1, -1, -1, -1, -1, -1, -1, -1))
+    )
+    binaryRegressionTests.foreach { case (b1, b2) =>
+      testPrefixComparison(b1, b2)
+    }
+
     // scalastyle:off
     val regressionTests = Table(
       ("s1", "s2"),
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/TypeUtils.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/TypeUtils.scala
index 7101ca5a17..45225779bf 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/TypeUtils.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/TypeUtils.scala
@@ -70,7 +70,9 @@ object TypeUtils {
 
   def compareBinary(x: Array[Byte], y: Array[Byte]): Int = {
     for (i <- 0 until x.length; if i < y.length) {
-      val res = x(i).compareTo(y(i))
+      val v1 = x(i) & 0xff
+      val v2 = y(i) & 0xff
+      val res = v1 - v2
       if (res != 0) return res
     }
     x.length - y.length
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/OrderingSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/OrderingSuite.scala
index 190fab5d24..aa61ba2bff 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/OrderingSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/OrderingSuite.scala
@@ -137,4 +137,23 @@ class OrderingSuite extends SparkFunSuite with ExpressionEvalHelper {
     // verify that we can support up to 5000 ordering comparisons, which should be sufficient
     GenerateOrdering.generate(Array.fill(5000)(sortOrder))
   }
+
+  test("SPARK-21344: BinaryType comparison does signed byte array comparison") {
+    val data = Seq(
+      (Array[Byte](1), Array[Byte](-1)),
+      (Array[Byte](1, 1, 1, 1, 1), Array[Byte](1, 1, 1, 1, -1)),
+      (Array[Byte](1, 1, 1, 1, 1, 1, 1, 1, 1), Array[Byte](1, 1, 1, 1, 1, 1, 1, 1, -1))
+      )
+    data.foreach { case (b1, b2) =>
+      val rowOrdering = InterpretedOrdering.forSchema(Seq(BinaryType))
+      val genOrdering = GenerateOrdering.generate(
+        BoundReference(0, BinaryType, nullable = true).asc :: Nil)
+      val rowType = StructType(StructField("b", BinaryType, nullable = true) :: Nil)
+      val toCatalyst = CatalystTypeConverters.createToCatalystConverter(rowType)
+      val rowB1 = toCatalyst(Row(b1)).asInstanceOf[InternalRow]
+      val rowB2 = toCatalyst(Row(b2)).asInstanceOf[InternalRow]
+      assert(rowOrdering.compare(rowB1, rowB2) < 0)
+      assert(genOrdering.compare(rowB1, rowB2) < 0)
+    }
+  }
 }
diff --git a/sql/core/src/test/resources/sql-tests/inputs/comparator.sql b/sql/core/src/test/resources/sql-tests/inputs/comparator.sql
new file mode 100644
index 0000000000..3e2447723e
--- /dev/null
+++ b/sql/core/src/test/resources/sql-tests/inputs/comparator.sql
@@ -0,0 +1,3 @@
+-- binary type
+select x'00' < x'0f';
+select x'00' < x'ff';
diff --git a/sql/core/src/test/resources/sql-tests/results/comparator.sql.out b/sql/core/src/test/resources/sql-tests/results/comparator.sql.out
new file mode 100644
index 0000000000..afc7b5448b
--- /dev/null
+++ b/sql/core/src/test/resources/sql-tests/results/comparator.sql.out
@@ -0,0 +1,18 @@
+-- Automatically generated by SQLQueryTestSuite
+-- Number of queries: 2
+
+
+-- !query 0
+select x'00' < x'0f'
+-- !query 0 schema
+struct<(X'00' < X'0F'):boolean>
+-- !query 0 output
+true
+
+
+-- !query 1
+select x'00' < x'ff'
+-- !query 1 schema
+struct<(X'00' < X'FF'):boolean>
+-- !query 1 output
+true