[10] After his stint with the Marlins, Garrett briefly decided to leave baseball and begin a full-time career in real estate.

In 2021 he connected with a former Marlins scout on LinkedIn, who helped him try out and sign a minor league contract with the Arizona Diamondbacks on March 19, 2021.

[11] Garrett spent the majority of the season with the Double-A Amarillo Sod Poodles, also playing in two games for the Triple-A Reno Aces.

[12][13] In his debut against the San Francisco Giants, Garrett recorded his first two career hits as part of a two-double, one-RBI game.

[14] On August 28, he hit his first career home run, a solo shot off of Chicago White Sox starter Dylan Cease.

[20] In an August 23 game against the New York Yankees, Garrett landed awkwardly against the outfield wall while attempting to catch a DJ LeMahieu fly ball.

In his first at-bat, Garrett hit a two-run home run off of Philadelphia Phillies pitcher Ranger Suárez to increase the Nationals' lead to 3–0.