He has previously played in Major League Baseball (MLB) for the New York Yankees, Miami Marlins, and Arizona Diamondbacks.

He was named the South Atlantic League player of the week on April 28 after setting a RiverDogs strikeout record with 13.

[7] On December 8, 2016, Smith was selected by the Milwaukee Brewers in the 2016 Rule 5 draft and then traded to the Chicago Cubs.

[11] On November 20, 2017, Smith was traded to the Miami Marlins along with Garrett Cooper in exchange for pitcher Mike King and international bonus pool money.

[12] Smith earned a spot in the Marlins' Opening Day starting rotation and was pitching effectively until he severely strained and tore his lat muscle from the bone during a game against the Rockies on June 26.

Smith earned a spot in the 2019 Opening Day rotation and had a stretch of six consecutive quality starts from April 7 through May 7.

[15] On August 31, 2020, Smith was traded from the Marlins alongside pitcher Humberto Mejía and Julio Frias to the Arizona Diamondbacks in a package deal for outfielder Starling Marte.

On August 18, 2021, Smith was suspended for ten games by Major League Baseball for having a foreign substance in his glove.

In the final day of the season, Smith left a game against the Los Angeles Dodgers with what was later diagnosed as a partial tear in the ulnar collateral ligament of his throwing arm.