On August 21, 2017, Gardewine was selected to the 40-man roster and promoted to the major leagues for the first time.[6][7] Gardewine appeared in 12 games for Texas in 2017, producing a 5.63 ERA with three strikeouts over eight innings of work.
In 2018 Gardewine appeared in three games for Texas, recording a 3.60 ERA with four strikeouts across 5 innings. He appeared in 12 games for the Round Rock Express of the Triple-APacific Coast League, throwing 12 innings with a 2–1 record, 7.30 ERA, and 17 strikeouts in 12 games. Gardewine was placed on the Triple-A disabled list on May 17, 2018, with a right forearm strain.[8] Gardewine spent the rest of the 2018 season rehabbing his injury and did not appear in another game. He was subsequently transferred to the 60-day injured list on August 25.
In 2019, Gardewine was optioned to the Nashville Sounds of the Triple-APacific Coast League to open the season, and appeared in four games before being shut down for the season due to injuries.[9] On June 8, he was designated for assignment by the Rangers.[10] On June 13, Gardewine was released by Texas. However, on June 19, he re-signed with the Rangers organization on a two-year minor league contract.[11]
Gardewine did not pitch for the organization in 2020 due to the cancellation of the minor league season because of the COVID-19 pandemic.[12] Gardewine was released by the Rangers on June 1, 2020.
On May 20, 2021, Gardewine’s contract was purchased by the Arizona Diamondbacks organization.[14] He made six appearances split between the rookie-level Arizona Complex League Diamondbacks and Triple-A Reno Aces, recording a 6.35 ERA with 10 strikeouts across 5+2⁄3 innings pitched. Gardewine was released by the Diamondbacks organization on July 29.
On January 23, 2023, he was released by the Railroaders.[16] Gardewine re–signed with Cleburne on June 17.[17] He made 24 appearances for the Railroaders, struggling to a 6.17 ERA with 24 strikeouts and 5 saves across 23+1⁄3 innings pitched. Gardewine became a free agent after the 2023 season.
On October 23, 2024, Gardewine signed with the Dorados de Chihuahua of the Mexican League.[20] In 13 appearances for Chihuahua in 2025, he struggled to a 1-1 record and 11.81 ERA with nine strikeouts and two saves across 10+2⁄3 innings pitched.
El Águila de Veracruz
On June 20, 2025, Gardewine was traded to El Águila de Veracruz of the Mexican League.[21] In 16 games he threw 16 innings of relief going 2-0 with a 2.25 ERA with 14 strikeouts and one save.
