On January 28, 2009, news agencies reported that Jon Garland had reached an agreement with the Arizona Diamondbacks for a one year deal with an option in 2010. In 2008, Garland finished the season with a 4.90 earned run average and a record of 14-8.ESPN.com: [Report: D-Backs, Garland agree to deal] (January 28, 2009)

Garland was traded the following year, to the Chicago White Sox on July 29, 1998. On July 4, 2000, Garland was called up to make his MLB debut with the White Sox. He played a total of 13 games that season, finishing with a 6.46 ERA in 69.7 innings pitched. He continued to split his time between the White Sox and their minor league teams, averaging 30-35 games with the White Sox each season.

In 2005, Garland made his first post season appearance, when the White Sox won the World Series over the Houston Astros. He was also selected for the MLB All-Star Game, although did not play.

Garland was traded to the Los Angeles Angels of Anaheim on November 19, 2007.