[1][2] The Cincinnati Reds selected Stallings in the 42nd round of the 2011 MLB draft, but he did not sign, and returned to North Carolina for his senior year.

Stallings made his professional debut that same year with the State College Spikes, where he batted .230/.324/.332 in 66 games.

[citation needed] On September 23, he had a game-winning RBI single in the Pirates' 6–5 win over the Washington Nationals.

[8] He was outrighted off the roster on May 17, 2019,[9] but was promoted back to the major leagues on May 26 when Francisco Cervelli went on the injured list.

[14][15] On November 29, 2021, the Pirates traded Stallings to the Miami Marlins for Zach Thompson and minor leaguers Kyle Nicolas and Connor Scott.

[17] On January 13, 2023, Stallings agreed to a one-year, $3.35 million contract with the Marlins, avoiding salary arbitration.

[18] On May 3, Stallings replaced Devin Smeltzer as the pitcher in the ninth inning of a game against the Atlanta Braves.

After recording a double play, Stallings faced April NL Player of the Month Ronald Acuña Jr., whom he struck out on four pitches.

[21] Stallings' father, Kevin, was formerly the head basketball coach at Illinois State, Vanderbilt, and Pittsburgh.