He has previously played in MLB for the Pittsburgh Pirates, San Diego Padres, Cleveland Guardians, Miami Marlins, and Arizona Diamondbacks.

Bell attended Jesuit College Preparatory School of Dallas and was selected by the Pirates in the second round of the 2011 MLB draft.

He received a $5 million signing bonus, a record for a player outside of the first round, to bypass his college baseball scholarship to the University of Texas at Austin.

However, Bell sent a letter to the Commissioner of Baseball's office, indicating that teams should not select him, because he would follow through with his commitment to Texas, and would not sign a professional contract if drafted.

Bell took twelve credits at the University of Texas and worked out with the team's strength and conditioning coach during the summer.

[10] Bell opened the 2014 season with the Bradenton Marauders of the High–A Florida State League (FSL), and appeared in the 2014 All-Star Futures Game.

[11] After hitting .335 with nine home runs and 35 RBI for Bradenton in 84 games, the Pirates promoted Bell to the Altoona Curve of the Double–A Eastern League on July 17.

He batted .347 with two home runs, 18 RBI, and a .441 on-base percentage in 145 plate appearances with Indianapolis, and the Pirates added Bell to their 40-man roster after the season.

On September 4, Bell broke the National League record for most home runs by a rookie switch hitter, hitting his 24th of the season off of Jake Arrieta, in a 12–0 Pirates' victory over the Chicago Cubs.

[22] He was one of three finalists for the 2017 Rookie of the Year award along with Cody Bellinger and Paul DeJong,[23] and finished in third place in the balloting.

[34] On December 24, 2020, the Pirates traded Bell to the Washington Nationals in exchange for Wil Crowe and Eddy Yean.

[37] In his final year of eligibility for salary arbitration, Bell signed a $10 million contract with the Nationals before the 2022 season.

[39] On August 2, 2022, Bell, along with Juan Soto, was traded to the San Diego Padres in exchange for C. J. Abrams, MacKenzie Gore, Robert Hassell III, James Wood, Jarlín Susana and Luke Voit.

[43] On August 1, 2023, Bell was traded to the Miami Marlins in exchange for infielders Jean Segura and Kahlil Watson.

[46] On July 30, 2024, the Marlins traded Bell to the Arizona Diamondbacks in exchange for cash considerations or a player to be named later.