Cotts attended Illinois State University where he won first-team All-Missouri Valley Conference honors and was named to the ABCA All-Midwest Region team.

Cotts finished his collegiate career ranked fifth all-time in school history in strikeouts with 263 in just three seasons with the Redbirds.

Cotts spent the 2002 season at Single-A Modesto of the California League, winning 12 games in 28 starts.

During the off-season, he was traded to the Chicago White Sox in a six-player deal involving relief pitchers Billy Koch and Keith Foulke.

Cotts made his Major League debut for Chicago on August 12, 2003, when he started against the Anaheim Angels.

In 2005, Cotts went 4–0 while appearing in 69 games, throwing 60.1 innings, compiling a 1.94 ERA, striking out 58, and yielding just 1 home run.

He would be recalled from Triple–A, however, in May and remained with Cubs as their primary left handed reliever after the club had traded away veteran pitcher Scott Eyre.

On January 4, 2010, Cotts signed a minor-league contract with the Pittsburgh Pirates with an invite to spring training.

On November 22, 2010, Cotts signed a minor league contract with the New York Yankees with an invitation to 2011 spring training.

Cotts signed with the Texas Rangers and was in contention in spring training to return to the Major Leagues, but suffered an arm strain injury.

He finally appeared in a professional game for the first time since 2009 on June 11, 2012, pitching for the Texas Rangers' Triple-A affiliate Round Rock.

On November 12, 2012, Cotts signed a minor league deal with an invitation to spring training to return to the Rangers organization.

[14] On June 20, 2016, Cotts signed a minor league contract to return to the Texas Rangers organization.