diff --git a/system/I18n/TimeLegacy.php b/system/I18n/TimeLegacy.php
index b62877ec40d6..7dfa0526304a 100644
--- a/system/I18n/TimeLegacy.php
+++ b/system/I18n/TimeLegacy.php
@@ -14,6 +14,8 @@
 namespace CodeIgniter\I18n;
 
 use DateTime;
+use Exception;
+use ReturnTypeWillChange;
 
 /**
  * Legacy Time class.
@@ -47,4 +49,21 @@
 class TimeLegacy extends DateTime
 {
     use TimeTrait;
+
+    /**
+     * Returns a new instance with the date set to the new timestamp.
+     *
+     * @param int $timestamp
+     *
+     * @return static
+     *
+     * @throws Exception
+     */
+    #[ReturnTypeWillChange]
+    public function setTimestamp($timestamp)
+    {
+        $time = date('Y-m-d H:i:s', $timestamp);
+
+        return static::parse($time, $this->timezone, $this->locale);
+    }
 }
diff --git a/system/I18n/TimeTrait.php b/system/I18n/TimeTrait.php
index 397d9a5a870d..e3808942e335 100644
--- a/system/I18n/TimeTrait.php
+++ b/system/I18n/TimeTrait.php
@@ -685,23 +685,6 @@ public function setTimezone($timezone)
         return static::createFromInstance($this->toDateTime()->setTimezone($timezone), $this->locale);
     }
 
-    /**
-     * Returns a new instance with the date set to the new timestamp.
-     *
-     * @param int $timestamp
-     *
-     * @return static
-     *
-     * @throws Exception
-     */
-    #[ReturnTypeWillChange]
-    public function setTimestamp($timestamp)
-    {
-        $time = date('Y-m-d H:i:s', $timestamp);
-
-        return static::parse($time, $this->timezone, $this->locale);
-    }
-
     // --------------------------------------------------------------------
     // Add/Subtract
     // --------------------------------------------------------------------
diff --git a/tests/system/I18n/TimeTest.php b/tests/system/I18n/TimeTest.php
index 10e38e2110a2..25ae527575d8 100644
--- a/tests/system/I18n/TimeTest.php
+++ b/tests/system/I18n/TimeTest.php
@@ -18,6 +18,7 @@
 use CodeIgniter\Test\CIUnitTestCase;
 use Config\App;
 use DateTime;
+use DateTimeImmutable;
 use DateTimeZone;
 use IntlDateFormatter;
 use Locale;
@@ -719,13 +720,28 @@ public function testSetTimezone(): void
 
     public function testSetTimestamp(): void
     {
-        $time  = Time::parse('May 10, 2017', 'America/Chicago');
-        $stamp = strtotime('April 1, 2017');
-        $time2 = $time->setTimestamp($stamp);
+        $time1 = Time::parse('May 10, 2017', 'America/Chicago');
+
+        $stamp = strtotime('2017-04-01'); // We use UTC as the default timezone.
+        $time2 = $time1->setTimestamp($stamp);
 
         $this->assertInstanceOf(Time::class, $time2);
-        $this->assertNotSame($time, $time2);
-        $this->assertSame('2017-04-01 00:00:00', $time2->toDateTimeString());
+        $this->assertSame('2017-05-10 00:00:00 -05:00', $time1->format('Y-m-d H:i:s P'));
+        $this->assertSame('2017-03-31 19:00:00 -05:00', $time2->format('Y-m-d H:i:s P'));
+    }
+
+    public function testSetTimestampDateTimeImmutable(): void
+    {
+        $time1 = new DateTimeImmutable(
+            'May 10, 2017',
+            new DateTimeZone('America/Chicago')
+        );
+
+        $stamp = strtotime('2017-04-01'); // We use UTC as the default timezone.
+        $time2 = $time1->setTimestamp($stamp);
+
+        $this->assertSame('2017-05-10 00:00:00 -05:00', $time1->format('Y-m-d H:i:s P'));
+        $this->assertSame('2017-03-31 19:00:00 -05:00', $time2->format('Y-m-d H:i:s P'));
     }
 
     public function testToDateString(): void
diff --git a/user_guide_src/source/changelogs/v4.6.0.rst b/user_guide_src/source/changelogs/v4.6.0.rst
index 51c43456ae28..2077164e8ba1 100644
--- a/user_guide_src/source/changelogs/v4.6.0.rst
+++ b/user_guide_src/source/changelogs/v4.6.0.rst
@@ -71,6 +71,12 @@ Time with Microseconds
 Fixed bugs that some methods in ``Time`` to lose microseconds have been fixed.
 See :ref:`Upgrading Guide <upgrade-460-time-keeps-microseconds>` for details.
 
+Time::setTimestamp()
+--------------------
+
+``Time::setTimestamp()`` behavior has been fixed.
+See :ref:`Upgrading Guide <upgrade-460-time-set-timestamp>` for details.
+
 .. _v460-interface-changes:
 
 Interface Changes
diff --git a/user_guide_src/source/installation/upgrade_460.rst b/user_guide_src/source/installation/upgrade_460.rst
index 5cbfd664bf92..da0875849156 100644
--- a/user_guide_src/source/installation/upgrade_460.rst
+++ b/user_guide_src/source/installation/upgrade_460.rst
@@ -85,6 +85,25 @@ Also, methods that returns an ``int`` still lose the microseconds.
 .. literalinclude:: upgrade_460/005.php
    :lines: 2-
 
+.. _upgrade-460-time-set-timestamp:
+
+Time::setTimestamp() Behavior Fix
+=================================
+
+In previous versions, if you call ``Time::setTimestamp()`` on a Time instance with
+a timezone other than the default timezone might return a Time instance with the
+wrong date/time.
+
+This bug has been fixed, and it now behaves in the same way as ``DateTimeImmutable``:
+
+.. literalinclude:: upgrade_460/008.php
+   :lines: 2-
+
+Note that if you use the default timezone, the behavior is not changed:
+
+.. literalinclude:: upgrade_460/009.php
+   :lines: 2-
+
 .. _upgrade-460-registrars-with-dirty-hack:
 
 Registrars with Dirty Hack
diff --git a/user_guide_src/source/installation/upgrade_460/008.php b/user_guide_src/source/installation/upgrade_460/008.php
new file mode 100644
index 000000000000..5a778de09c53
--- /dev/null
+++ b/user_guide_src/source/installation/upgrade_460/008.php
@@ -0,0 +1,18 @@
+<?php
+
+use CodeIgniter\I18n\Time;
+
+// The Application Timezone is "UTC".
+
+// Set $time1 timezone to "America/Chicago".
+$time1 = Time::parse('2024-08-20', 'America/Chicago');
+
+// The timestamp is "2024-08-20 00:00" in "UTC".
+$stamp = strtotime('2024-08-20'); // 1724112000
+
+// But $time2 timezone is "America/Chicago".
+$time2 = $time1->setTimestamp($stamp);
+
+echo $time2->format('Y-m-d H:i:s P');
+// Before: 2024-08-20 00:00:00 -05:00
+//  After: 2024-08-19 19:00:00 -05:00
diff --git a/user_guide_src/source/installation/upgrade_460/009.php b/user_guide_src/source/installation/upgrade_460/009.php
new file mode 100644
index 000000000000..f00daa0b63b0
--- /dev/null
+++ b/user_guide_src/source/installation/upgrade_460/009.php
@@ -0,0 +1,18 @@
+<?php
+
+use CodeIgniter\I18n\Time;
+
+// The Application Timezone is "America/Chicago".
+
+// $time1 timezone is "America/Chicago".
+$time1 = Time::parse('2024-08-20');
+
+// The timestamp is "2024-08-20 00:00" in "America/Chicago".
+$stamp = strtotime('2024-08-20'); // 1724130000
+
+// $time2 timezone is also "America/Chicago".
+$time2 = $time1->setTimestamp($stamp);
+
+echo $time2->format('Y-m-d H:i:s P');
+// Before: 2024-08-20 00:00:00 -05:00
+//  After: 2024-08-20 00:00:00 -05:00
diff --git a/user_guide_src/source/libraries/time.rst b/user_guide_src/source/libraries/time.rst
index 9fd986d31421..17af069c8c5f 100644
--- a/user_guide_src/source/libraries/time.rst
+++ b/user_guide_src/source/libraries/time.rst
@@ -314,6 +314,9 @@ Returns a new instance with the date set to the new timestamp:
 
 .. literalinclude:: time/030.php
 
+.. note:: Prior to v4.6.0, due to a bug, this method might return incorrect
+    date/time. See :ref:`Upgrading Guide <upgrade-460-time-set-timestamp>` for details.
+
 Modifying the Value
 ===================
 
diff --git a/user_guide_src/source/libraries/time/030.php b/user_guide_src/source/libraries/time/030.php
index 1e22876e9883..5ca37d326925 100644
--- a/user_guide_src/source/libraries/time/030.php
+++ b/user_guide_src/source/libraries/time/030.php
@@ -2,7 +2,9 @@
 
 use CodeIgniter\I18n\Time;
 
-$time  = Time::parse('May 10, 2017', 'America/Chicago');
+// The Application Timezone is "America/Chicago".
+
+$time  = Time::parse('May 10, 2017');
 $time2 = $time->setTimestamp(strtotime('April 1, 2017'));
 
 echo $time->toDateTimeString();  // 2017-05-10 00:00:00