The Astros invited Dubin to their Spring Training in 2021.[7] He did not make the team and spent the year with the Triple-A Sugar Land Skeeters, working to a 3.44 ERA with 69 strikeouts in 49.2 innings of work across 16 contests. He was selected to the 40-man roster following the season on November 19, 2021.[8]
Dubin was optioned to the Triple-A Sugar Land Space Cowboys to begin the 2023 season.[9] In 9 games (5 starts), he struggled to a 7.96 ERA with 25 strikeouts in 26.0 innings pitched. On June 18, 2023, Dubin was promoted to the major leagues for the first time.[10] He had fifteen friends and family fly to Houston from Western New York but did not appear in that day's game.[2] He made his debut on June 19 against the New York Mets and struck out the first batter he faced, Brandon Nimmo. He pitched two scoreless innings but allowed five runs in his third inning of work.[11] Dubin made his first MLB start on July 2, allowing one run in four innings against the Texas Rangers at Globe Life Field.[12] Following the game, the Astros added Brandon Bielak to the active roster and sent Dubin to Triple-A.[13] Dubin finished the year in the minors, spending about three weeks of August on the injured list.[14]
In 2024, Dubin appeared in 31 games for the major league club, posting a 1–1 W–L, 4.17 ERA, 45 hits, 26 bases on balls, 1.566 walks plus hits per inning pitched (WHIP) and 49 strikeouts over 45+1⁄3 innings. He filled a variety of roles, including 2 games started as opener, 2 saves, and 11 games finished.[15] At Sugar Land in 2024, Dubin made 10 appearances, was 2–0, pitched 10 innings, allowed 4 runs with 8 hits and 5 strikeouts, and struck out 13,[16]
^News-Graphic, Kal Oakes Georgetown (July 2, 2020). "Tigers' alum Dubin on MLB call". News-Graphic.com. Archived from the original on May 2, 2021. Retrieved March 9, 2021.