diff --git a/tests/phpunit/tests/date/currentTime.php b/tests/phpunit/tests/date/currentTime.php
index 0c4ff698d1..66c2fdf3c5 100644
--- a/tests/phpunit/tests/date/currentTime.php
+++ b/tests/phpunit/tests/date/currentTime.php
@@ -128,4 +128,33 @@ class Tests_Date_CurrentTime extends WP_UnitTestCase {
 		$this->assertEqualsWithDelta( strtotime( $datetime_local->format( DATE_W3C ) ), strtotime( current_time( DATE_W3C ) ), 2, 'The dates should be equal' );
 		$this->assertEqualsWithDelta( strtotime( $datetime_utc->format( DATE_W3C ) ), strtotime( current_time( DATE_W3C, true ) ), 2, 'The dates should be equal' );
 	}
+
+	/**
+	 * Ensures that deprecated timezone strings are handled correctly.
+	 *
+	 * @ticket 56468
+	 */
+	public function test_should_work_with_deprecated_timezone() {
+		$format          = 'Y-m-d H:i';
+		$timezone_string = 'America/Buenos_Aires'; // This timezone was deprecated pre-PHP 5.6.
+		update_option( 'timezone_string', $timezone_string );
+		$datetime = new DateTime( 'now', new DateTimeZone( $timezone_string ) );
+
+		// phpcs:ignore WordPress.DateTime.RestrictedFunctions.timezone_change_date_default_timezone_set
+		date_default_timezone_set( $timezone_string );
+
+		$current_time_custom_timezone_gmt = current_time( $format, true );
+		$current_time_custom_timezone     = current_time( $format );
+
+		// phpcs:ignore WordPress.DateTime.RestrictedFunctions.timezone_change_date_default_timezone_set
+		date_default_timezone_set( 'UTC' );
+
+		$current_time_gmt = current_time( $format, true );
+		$current_time     = current_time( $format );
+
+		$this->assertSame( gmdate( $format ), $current_time_custom_timezone_gmt, 'The dates should be equal [1]' );
+		$this->assertSame( $datetime->format( $format ), $current_time_custom_timezone, 'The dates should be equal [2]' );
+		$this->assertSame( gmdate( $format ), $current_time_gmt, 'The dates should be equal [3]' );
+		$this->assertSame( $datetime->format( $format ), $current_time, 'The dates should be equal [4]' );
+	}
 }
diff --git a/tests/phpunit/tests/date/dateI18n.php b/tests/phpunit/tests/date/dateI18n.php
index b52f43e0e2..dfc98dd369 100644
--- a/tests/phpunit/tests/date/dateI18n.php
+++ b/tests/phpunit/tests/date/dateI18n.php
@@ -108,6 +108,23 @@ class Tests_Date_DateI18n extends WP_UnitTestCase {
 		$this->assertSame( '2012-12-01 00:00:00 CST -06:00 America/Regina', date_i18n( 'Y-m-d H:i:s T P e', strtotime( '2012-12-01 00:00:00' ) ) );
 	}
 
+	/**
+	 * Ensures that deprecated timezone strings are handled correctly.
+	 *
+	 * @ticket 56468
+	 */
+	public function test_adjusts_format_based_on_deprecated_timezone_string() {
+		update_option( 'timezone_string', 'America/Buenos_Aires' ); // This timezone was deprecated pre-PHP 5.6.
+
+		$expected = '2022-08-01 00:00:00 -03 -03:00 America/Buenos_Aires';
+		if ( PHP_VERSION_ID < 70000 ) {
+			// PHP 5.6.
+			$expected = '2022-08-01 00:00:00 ART -03:00 America/Buenos_Aires';
+		}
+
+		$this->assertSame( $expected, date_i18n( 'Y-m-d H:i:s T P e', strtotime( '2022-08-01 00:00:00' ) ) );
+	}
+
 	/**
 	 * @ticket 34835
 	 */
diff --git a/tests/phpunit/tests/date/mysql2date.php b/tests/phpunit/tests/date/mysql2date.php
index e8418467c7..2ae4939c56 100644
--- a/tests/phpunit/tests/date/mysql2date.php
+++ b/tests/phpunit/tests/date/mysql2date.php
@@ -62,6 +62,22 @@ class Tests_Date_mysql2date extends WP_UnitTestCase {
 		$this->assertSame( $rfc3339, mysql2date( DATE_RFC3339, $mysql, false ) );
 	}
 
+	/**
+	 * Ensures that deprecated timezone strings are handled correctly.
+	 *
+	 * @ticket 56468
+	 */
+	public function test_mysql2date_should_format_time_with_deprecated_time_zone() {
+		$timezone = 'America/Buenos_Aires'; // This timezone was deprecated pre-PHP 5.6.
+		update_option( 'timezone_string', $timezone );
+		$datetime = new DateTime( 'now', new DateTimeZone( $timezone ) );
+		$rfc3339  = $datetime->format( DATE_RFC3339 );
+		$mysql    = $datetime->format( 'Y-m-d H:i:s' );
+
+		$this->assertSame( $rfc3339, mysql2date( DATE_RFC3339, $mysql ) );
+		$this->assertSame( $rfc3339, mysql2date( DATE_RFC3339, $mysql, false ) );
+	}
+
 	/**
 	 * @ticket 28992
 	 */
diff --git a/tests/phpunit/tests/date/wpTimezone.php b/tests/phpunit/tests/date/wpTimezone.php
index e48a1b03b5..3e8b6fef5f 100644
--- a/tests/phpunit/tests/date/wpTimezone.php
+++ b/tests/phpunit/tests/date/wpTimezone.php
@@ -51,6 +51,22 @@ class Tests_Date_wpTimezone extends WP_UnitTestCase {
 		$this->assertSame( 'Europe/Helsinki', $timezone->getName() );
 	}
 
+	/**
+	 * Ensures that deprecated timezone strings are handled correctly.
+	 *
+	 * @ticket 56468
+	 */
+	public function test_should_return_deprecated_timezone_string() {
+		$tz_string = 'America/Buenos_Aires'; // This timezone was deprecated pre-PHP 5.6.
+		update_option( 'timezone_string', $tz_string );
+
+		$this->assertSame( $tz_string, wp_timezone_string() );
+
+		$timezone = wp_timezone();
+
+		$this->assertSame( $tz_string, $timezone->getName() );
+	}
+
 	/**
 	 * Data provider to test numeric offset conversion.
 	 *
diff --git a/tests/phpunit/tests/formatting/date.php b/tests/phpunit/tests/formatting/date.php
index d3e0971789..684cf86d97 100644
--- a/tests/phpunit/tests/formatting/date.php
+++ b/tests/phpunit/tests/formatting/date.php
@@ -240,6 +240,11 @@ class Tests_Formatting_Date extends WP_UnitTestCase {
 				'timezone_string' => '',
 				'gmt_offset'      => 3,
 			),
+			// @ticket 56468.
+			'deprecated timezone string and no GMT offset set' => array(
+				'timezone_string' => 'America/Buenos_Aires',
+				'gmt_offset'      => 0,
+			),
 		);
 	}
 }