He was one of five Reds prospects invited to the team's 2023 spring training camp.[10] Abbott began the year with Double-A Chattanooga, posting a 1.15 ERA across 3 starts before he promoted to the Triple-A Louisville Bats.[11] In 7 starts for Louisville, Abbott logged a 3–0 record and 3.05 ERA with 54 strikeouts in 38+1⁄3 innings of work.[12]
On June 4, 2023, the Reds announced that Abbott would be promoted to the major leagues for the first time to start against the Milwaukee Brewers the following day, after Hunter Greene had his start pushed back due to hip stiffness.[13] Abbott made his major league debut on June 5 and threw 6 shutout innings versus the Brewers, striking out 6 batters and allowing only 1 hit, making him the only left-hander in the Modern Era to pitch at least 6 scoreless innings with at least 6 strikeouts and no more than one hit allowed in an MLB debut, and the first Reds pitcher to do so since 1893.[14] On June 16, Abbott surrendered four hits over six scoreless innings versus the Houston Astros to become first MLB pitcher to hurl three scoreless starts of at least five innings since 1893 when the mound was moved to its current distance of 60 feet, 6 inches.[15]