He has previously played in MLB for the Detroit Tigers, Washington Nationals, and Baltimore Orioles and in Nippon Professional Baseball (NPB) for the Saitama Seibu Lions.

[3] Garrett spent his professional debut season of 2014 with the Spokane Indians of the Low–A Northwest League, posting a 6–1 record with a 4.06 ERA and 46 strikeouts in 57.2 innings over 16 games (9 starts).

[4] He spent the 2017 season with Frisco, posting a 2–5 record with a 4.98 ERA, 70 strikeouts, and 68.2 innings pitched in 44 games (4 starts).

In 2018, Garrett became a full time relief pitcher and split the season between Frisco and the Round Rock Express of the Triple-A Pacific Coast League, posting a combined 4–2 record with a 2.04 ERA, 61 strikeouts, and 61.2 innings pitched over 51 games.

[9] He made his major league debut on March 29 versus the Toronto Blue Jays, recording one strikeout over one inning of relief.

He was then assigned to the Nashville Sounds of the Triple-A Pacific Coast League for the remainder of the season,[11] going 1–3 with a 4.91 ERA in 40 innings.

On June 14, Garrett had his contract selected to the major league roster after Austin Voth was placed on the injured list.

[22] Despite a 5-0 record between April 4 and May 19 with two saves, four holds, 2 earned runs and 41 strikeouts during that time, his performance declined after that point, before improving in the last part of August and September.