Chatwood was drafted by the Los Angeles Angels of Anaheim in the second round of the 2008 Major League Baseball draft out of Redlands East Valley High School. Chatwood made his major league debut on April 11, 2011 in a loss against the Cleveland Indians where he went five innings, giving up four runs on four hits with three strikeouts and four walks. In his second start against the Chicago White Sox he earned his first major league win, pitching seven innings, only giving up one run on five hits and two walks while striking out three. Chatwood remained in the rotation for most of the season, making 25 starts for the Angels. His hits allowed and inability to control his pitches led to him finishing with an ERA of 4.75 and a 6-11 record.
Colorado Rockies
On November 30, 2011, Chatwood was traded to the Colorado Rockies for catcher Chris Iannetta. Chatwood began the 2012 season in the Rockies bullpen, appearing in 4 games while recording 1 save. At the beginning of August, Chatwood was inserted in the rotation. He finished with a record of 5-6 with a 5.43 ERA in 19 games. In 2013, Chatwood had his best season despite missing half the season because of injury. Chatwood made 20 starts, going 8-5 with a 3.15 ERA and inducing an over 50% groundball rate for the Rockies. In July 2014, Chatwood underwent Tommy John surgery to repair the ulnar collateral ligament of the elbow in his pitching arm, ending his season after just 4 starts. He signed a two-year, $2 million extension with the Rockies on January 14, 2015. After sitting out the entire 2015 season to recover from Tommy John surgery, Chatwood came back healthy in 2016. He made 27 starts in 2016, posting a 12-9 record with a 3.87 ERA over 158 innings. Despite his struggles at Coors Field in 2016, Chatwood led all qualified pitchers in road ERA, he finished 2016, with a 1.69 road ERA over 80 innings and an 8-1 road record. In January 2017, Chatwood and the Rockies avoided arbitration. The two sides settled on a one-year deal for 4.4 million dollars for the 2017 season. On April 15, 2017, Chatwood retired the first 17 batters until giving up a single by Chris Marrero. Chatwood helped his own cause with a 2-run single, and pitched a complete game as the Rockies shut out the San Francisco Giants 5-0.
Chicago Cubs
On December 7, 2017, Chatwood signed a three-year, $38 million contract with the Chicago Cubs. On April 29, 2018, Chatwood hit an RBI single, scoring Addison Russell, for his first hit as a Chicago Cub. Chatwood began the 2018 season in Chicago's starting rotation, but after compiling a 4.98 ERA with 84 walks in 95 innings and the Cubs acquisition of Cole Hamels, he was moved to the bullpen. He finished the season 4-6 with a 5.30 ERA over 24 games. In 2019, he moved to the bullpen nearly full-time, going 5-3 with a 3.76 ERA over 38 games, striking out 74 batters over innings.
