diff --git a/velox/functions/prestosql/DateTimeFunctions.h b/velox/functions/prestosql/DateTimeFunctions.h
index e1c5b3b29aa9..d639d12fe68b 100644
--- a/velox/functions/prestosql/DateTimeFunctions.h
+++ b/velox/functions/prestosql/DateTimeFunctions.h
@@ -1118,7 +1118,7 @@ struct DateTruncFunction : public TimestampWithTimezoneSupport<T> {
         Timestamp::fromMillis(Timestamp::calendarUtcToEpoch(dateTime) * 1000);
     timestamp.toGMT(unpackZoneKeyId(timestampWithTimezone));
 
-    result = pack(timestamp.toMillis(), unpackZoneKeyId(timestampWithTimezone));
+    result = pack(timestamp, unpackZoneKeyId(timestampWithTimezone));
   }
 
  private:
@@ -1207,9 +1207,8 @@ struct DateAddFunction : public TimestampWithTimezoneSupport<T> {
       const arg_type<Varchar>& unitString,
       const int64_t value,
       const arg_type<TimestampWithTimezone>& timestampWithTimezone) {
-    const auto unit = unit_.has_value()
-        ? unit_.value()
-        : fromDateTimeUnitString(unitString, true /*throwIfInvalid*/).value();
+    const auto unit = unit_.value_or(
+        fromDateTimeUnitString(unitString, true /*throwIfInvalid*/).value());
 
     if (value != (int32_t)value) {
       VELOX_UNSUPPORTED("integer overflow");
@@ -1443,7 +1442,7 @@ struct FromIso8601Timestamp {
       tzID = sessionTzID_;
     }
     ts.toGMT(tzID);
-    result = pack(ts.toMillis(), tzID);
+    result = pack(ts, tzID);
     return Status::OK();
   }
 
@@ -1614,7 +1613,7 @@ struct ParseDateTimeFunction {
         ? dateTimeResult->timezoneId
         : sessionTzID_.value_or(0);
     dateTimeResult->timestamp.toGMT(timezoneId);
-    result = pack(dateTimeResult->timestamp.toMillis(), timezoneId);
+    result = pack(dateTimeResult->timestamp, timezoneId);
     return Status::OK();
   }
 };
diff --git a/velox/functions/prestosql/DateTimeImpl.h b/velox/functions/prestosql/DateTimeImpl.h
index 7a8430623492..0654c865abb0 100644
--- a/velox/functions/prestosql/DateTimeImpl.h
+++ b/velox/functions/prestosql/DateTimeImpl.h
@@ -204,13 +204,8 @@ FOLLY_ALWAYS_INLINE int64_t addToTimestampWithTimezone(
     const DateTimeUnit unit,
     const int32_t value) {
   auto timestamp = unpackTimestampUtc(timestampWithTimezone);
-  auto tzID = unpackZoneKeyId(timestampWithTimezone);
-  timestamp.toTimezone(tzID);
-
-  auto finalTimestamp = addToTimestamp(timestamp, unit, value);
-
-  finalTimestamp.toGMT(tzID);
-  return pack(finalTimestamp.toMillis(), tzID);
+  auto finalTimeStamp = addToTimestamp(timestamp, unit, (int32_t)value);
+  return pack(finalTimeStamp, unpackZoneKeyId(timestampWithTimezone));
 }
 
 FOLLY_ALWAYS_INLINE int64_t diffTimestamp(
diff --git a/velox/functions/prestosql/tests/DateTimeFunctionsTest.cpp b/velox/functions/prestosql/tests/DateTimeFunctionsTest.cpp
index 0396b9f8fd57..07afeafb234a 100644
--- a/velox/functions/prestosql/tests/DateTimeFunctionsTest.cpp
+++ b/velox/functions/prestosql/tests/DateTimeFunctionsTest.cpp
@@ -1089,8 +1089,17 @@ TEST_F(DateTimeFunctionsTest, timestampWithTimeZonePlusIntervalDayTime) {
       "2024-10-03 01:51:00.000 America/Los_Angeles",
       test("2024-10-03 01:50 America/Los_Angeles", 1 * kMillisInMinute));
 
-  // TODO Add tests for transitioning to/from DST once
-  // https://github.com/facebookincubator/velox/issues/10163 is fixed.
+  // Testing daylight saving transitions.
+
+  // At the beginning there is a 1 hour gap.
+  EXPECT_EQ(
+      "2024-03-10 01:30:00.000 America/Los_Angeles",
+      test("2024-03-10 03:30 America/Los_Angeles", -1 * kMillisInHour));
+
+  // At the end there is a 1 hour duplication.
+  EXPECT_EQ(
+      "2024-11-03 01:30:00.000 America/Los_Angeles",
+      test("2024-11-03 01:30 America/Los_Angeles", 1 * kMillisInHour));
 }
 
 TEST_F(DateTimeFunctionsTest, minusTimestamp) {
@@ -2403,6 +2412,31 @@ TEST_F(DateTimeFunctionsTest, dateAddTimestampWithTimeZone) {
       "year", 3, "1972-05-20+23:01:02+14:00", "1975-05-20+23:01:02+14:00");
   evaluateDateAddFromStrings(
       "year", 3, "1968-02-20+23:01:02+14:00", "1971-02-20+23:01:02+14:00");
+
+  // Tests date_add() on daylight saving transition boundaries.
+  //
+  // Presto's semantic is to apply the delta to GMT, which means that at times
+  // the observed delta may not be linear, in cases when it hits a daylight
+  // savings boundary.
+  auto dateAddAndCast = [&](std::optional<std::string> unit,
+                            std::optional<int32_t> value,
+                            std::optional<std::string> timestampString) {
+    return evaluateOnce<std::string>(
+        "cast(date_add(c0, c1, cast(c2 as timestamp with time zone)) as VARCHAR)",
+        unit,
+        value,
+        timestampString);
+  };
+
+  EXPECT_EQ(
+      "2024-03-10 03:50:00.000 America/Los_Angeles",
+      dateAddAndCast("hour", 1, "2024-03-10 01:50:00 America/Los_Angeles"));
+  EXPECT_EQ(
+      "2024-11-03 01:50:00.000 America/Los_Angeles",
+      dateAddAndCast("hour", 1, "2024-11-03 01:50:00 America/Los_Angeles"));
+  EXPECT_EQ(
+      "2024-11-03 00:50:00.000 America/Los_Angeles",
+      dateAddAndCast("hour", -1, "2024-11-03 01:50:00 America/Los_Angeles"));
 }
 
 TEST_F(DateTimeFunctionsTest, dateDiffDate) {
diff --git a/velox/functions/prestosql/types/TimestampWithTimeZoneType.h b/velox/functions/prestosql/types/TimestampWithTimeZoneType.h
index bbcc0b2b3431..85f0460c9df0 100644
--- a/velox/functions/prestosql/types/TimestampWithTimeZoneType.h
+++ b/velox/functions/prestosql/types/TimestampWithTimeZoneType.h
@@ -142,6 +142,10 @@ inline int64_t pack(int64_t millisUtc, int16_t timeZoneKey) {
   return (millisUtc << kMillisShift) | (timeZoneKey & kTimezoneMask);
 }
 
+inline int64_t pack(const Timestamp& timestamp, int16_t timeZoneKey) {
+  return pack(timestamp.toMillis(), timeZoneKey);
+}
+
 inline Timestamp unpackTimestampUtc(int64_t dateTimeWithTimeZone) {
   return Timestamp::fromMillis(unpackMillisUtc(dateTimeWithTimeZone));
 }