Maddux, who signed a free agent contract with the Cubs before the 2004 season, was traded to Los Angeles in exchange for infielder Cesar Izturis and cash considerations.
The 327-game winner started the season winning his first five starts but has struggled since, compiling an overall 9-11 record with 4.69 earned run average in 22 starts.
With his win Saturday, Maddux moved past Eddie Plank (326) for 12th on the all-time list and is one behind Jack Clarkson for 11th. In 21 seasons, Maddux is 327-200 with a 3.06 ERA and 3,133 strikeouts in 665 games.
Izturis, 26, has played in just 32 games this year after having his 2005 season cut short following elbow surgery in early September. He is hitting .252 with a homer and 12 RBI in 119 at-bats.