In 42 relief appearances between Lakeland, Charlotte, Durham, Montgomery, and Binghamton, Smith pitched to a 4-4 record with a 1.65 ERA and 0.90 WHIP.

Smith underwent Tommy John surgery during 2019 spring training, forcing him to miss the year.

[11] In 2021, although he missed time due to injury, Smith still made thirty relief appearances for the Mets, going 3-1 with a 2.40 ERA and 41 strikeouts over 41+1⁄3 innings.

Smith earned his first major league save in a game against the Washington Nationals, pitching +1⁄3 inning, on May 12, 2023.

[16] Smith made 62 relief outings for New York in 2023, registering a 4–6 record and 4.15 ERA with 60 strikeouts and 3 saves across 56+1⁄3 innings pitched.

Smith began the 2024 campaign as part of the Mets' bullpen, recording a 3.06 ERA with 23 strikeouts and 2 saves in 19 games.

On July 13, 2024, Smith underwent season-ending Tommy John surgery to repair his ulnar collateral ligament and would likely be out until 2026.