[9][10] Stewart enrolled at Eastern Florida State College (EFSC) for the 2018–19 academic year in order to be eligible for selection in the 2019 Major League Baseball draft.

[11] With the EFSC Titans, who compete in the National Junior College Athletic Association (NJCAA), Stewart made 13 starts, compiling a 2–2 record with 1.70 ERA and 108 strikeouts.

[12] On May 21, 2019, sports website The Athletic reported that Stewart agreed to contract terms with the Fukuoka SoftBank Hawks of Nippon Professional Baseball (NPB).

On April 17, 2021, Stewart made his NPB debut in the ninth inning of a game against the Saitama Seibu Lions.

On July 26, 2023, Stewart earned his first NPB win after tossing six scoreless innings in a 7–1 victory over the Orix Buffaloes.