He has previously played in MLB for the Toronto Blue Jays, Seattle Mariners, Detroit Tigers, and Cleveland Guardians.

[5] In the 2013 Major League Baseball Draft, the Toronto Blue Jays selected Boyd in the sixth round.

[6] Boyd was initially assigned to the Class-A Lansing Lugnuts, where he recorded a 0.64 earned run average in 14 innings before being promoted to the Advanced-A Dunedin Blue Jays, where he spent the remainder of the 2013 season.

[14] This money is distributed amongst the team and staff; typically, players who were traded or released through the year are awarded partial shares or grants from the playoff pool.

On July 30, 2015, the Blue Jays traded Boyd, Daniel Norris and Jairo Labourt to the Detroit Tigers in exchange for David Price.

Before being recalled, Boyd posted a 9–2 record and a 1.65 ERA in 19 starts between Double-A New Hampshire, Triple-A Buffalo and Toledo.

[20] Boyd was recalled from Toledo on April 24 and made one relief appearance against the Cleveland Indians, but was sent back to Triple-A shortly after.

[23] Boyd was back up with the Tigers by July 9, after both Jordan Zimmermann and Daniel Norris were placed on the disabled list within 24 hours of each other.

He made the best start of his young career on July 18, allowing no runs and only three hits in six innings against the Minnesota Twins, earning the win in a 1–0 decision.

[24] On August 13, Boyd had his longest start of the season to date, allowing just two hits and two walks over seven innings of a 2–0 win against the Texas Rangers.

[25] In a September 20 victory over the Twins, Boyd pitched a career-high eight innings, giving up just three hits and a run, while striking out seven.

[29] On September 17 against the Chicago White Sox, Boyd took a no-hitter into the ninth inning, until a two-out double by Tim Anderson ended the chance.

Boyd set career highs in 2018 with 31 starts and 170+1⁄3 innings pitched, posting a 9–13 record with a 4.39 ERA and 159 strikeouts.

[32][33][34] On July 4 against the Chicago White Sox, Boyd became the first pitcher in the live-ball era to record 13 strikeouts and zero walks in an appearance of six innings or fewer.

[47] He returned to the Tigers on August 29 to make his first start since the injury,[48] only to suffer a forearm issue in early September that ended his season.

[49] On March 20, 2022, Boyd finalized a deal with the San Francisco Giants on a one-year contract worth $5.2 million.

[50] On August 2, 2022, Boyd and Curt Casali were traded to the Seattle Mariners in exchange for Michael Stryffeler and Andy Thomas.

[56] The following day, it was announced that Boyd had been diagnosed with a partial sprain of his UCL and would undergo Tommy John surgery, ending his season.

On June 29, 2024, Boyd signed a one-year major league contract with the Cleveland Guardians and placed on the 15-day injured list while he recovered from elbow surgery.

[62] Boyd is distantly related to Hall of Fame pitcher Bob Feller, as well as former First Lady of the United States Dolley Madison.