Sterner made his professional debut in 2021 with the Single–A Jupiter Hammerheads, for whom he posted a 1.38 ERA across seven appearances. He was later promoted to the High–A Beloit Snappers, and compiled a 7.36 ERA with 10 strikeouts in five games.[5]
Sterner split the 2022 campaign between Montgomery and the Triple–A Durham Bulls. In 38 appearances for the two affiliates, he accumulated a 6–2 record and 3.94 ERA with 65 strikeouts across 48 innings of work.[7] Sterner played 2023 back with Montgomery and Durham, combining for a 5.27 ERA with 71 strikeouts and three saves in 34 total appearances.[8]
Sterner began the 2024 season in Durham, compiling a 3.60 ERA with 33 strikeouts across 25 innings pitched.[9] On May 31, 2024, Sterner was selected to the 40-man roster and promoted to the major leagues for the first time.[10]