Eligible in the 2011 MLB draft, the Cincinnati Reds selected Garrett in the 22nd round. He signed with the Reds, receiving a $1 million signing bonus and permission to continue his basketball career.[4] In the fall of 2011, Garrett enrolled at Bridgton Academy in Bridgton, Maine, where he played on the basketball team throughout the 2011–12 season.[5]
Garrett began the 2013 baseball season with Billings, but was promoted to the Dayton Dragons of the Single–AMidwest League in July.[13] He finished the season with a 5.15 ERA, 32 strikeouts, and 26 walks in 57+2⁄3 innings. He returned to Dayton for the start of the 2014 season.[1] In August 2014, Garrett decided to quit basketball and withdraw from Cal-State Northridge in order to focus on baseball.[14] He had a 7–8 record and a 3.65 ERA in 27 games started, and the Reds added him to their 40-man roster after the season.[15] He began the 2015 season with the Daytona Tortugas of the High–AFlorida State League (FSL),[16] and was chosen to represent the Reds at the 2015 All-Star Futures Game.[17] Garrett finished the 2015 season with a 2.44 ERA and 133 strikeouts for Daytona, and with Jacob Faria, was named the Co-FSL Pitcher of the Year.[18]
Garrett made the Reds' Opening Day roster in 2017.[22] In his major league debut on April 7 against the St. Louis Cardinals, Garrett went six shutout innings, giving up just two hits and earning the win in the Reds 2–0 victory over the Cardinals.[23]
On May 7, Garrett was optioned down to the Reds' Triple–A affiliate, the Louisville Bats, after Barrett Astin was recalled.[24] On May 25, Garrett was placed on the 10-day disabled list due to right hip inflammation.[25] Garrett was optioned and recalled multiple times during the season. In 14 starts for Louisville he was 2–4 with a 5.72 ERA, and in 16 games (14 starts) for Cincinnati, he compiled a 3–8 record and 7.39 ERA.[26]
Garrett began the 2018 season in the Cincinnati bullpen. In 66 games, he was 1–2 with a 4.29 ERA and 71 strikeouts in 63 innings.[27]
In 2020 for Cincinnati, Garrett appeared in 21 games, recording a 2.45 ERA with 26 strikeouts in 18+1⁄3 innings pitched.[29] Garrett had a 6.04 ERA in 63 appearances in 2021.[30]
Kansas City Royals
On March 16, 2022, the Reds traded Garrett to the Kansas City Royals in exchange for Mike Minor.[31] The Royals placed Garrett on the injured list on May 31.[32] He appeared in 16 contests for the team in 2022, recording a 4.96 ERA with 49 strikeouts in 45+1⁄3 innings of work.
On January 13, 2023, Garrett agreed to a one-year, $2.65 million contract with the Royals, avoiding salary arbitration.[33] He pitched in 27 games out of the bullpen for Kansas City, registering a 3.33 ERA with 28 strikeouts in 24+1⁄3 innings pitched. On July 9, he was designated for assignment by Kansas City after Ryan Yarbrough was activated from the injured list.[34] Garrett was released by the Royals on July 15.[35]
Cleveland Guardians
On July 25, 2023, Garrett signed a minor league contract with the Cleveland Guardians organization.[36] In 5 games for the Triple–A Columbus Clippers, he posted a 5.79 ERA with 4 strikeouts in 4+2⁄3 innings pitched. On August 24, Garrett requested and was granted his release by the Guardians.[37]
Los Angeles Angels
On February 12, 2024, Garrett signed a minor league contract with the San Francisco Giants.[38] He was released by the Giants on March 21 after being informed he would not make the Opening Day roster.[39]
On March 27, 2024, Garrett signed a minor league contract with the Los Angeles Angels.[40] In 8 games for the Triple–A Salt Lake Bees, he logged a 2.45 ERA with 10 strikeouts. On April 30, the Angels selected Garrett's contract, adding him to the major league roster.[41] In 6 games for Los Angeles, he recorded a 5.06 ERA with 11 strikeouts across 5+1⁄3 innings pitched. On May 15, Garrett was designated for assignment by the Angels.[42] He elected free agency on May 19.[43] Garrett re–signed with the Angels on a minor league contract on May 22.[44] He was released by the Angels organization on August 13.[45]
Personal
Garrett and his wife, Tausana, were engaged in 2018.[46]