Harris started his professional career that year with the Gulf Coast Braves before being promoted to the Rome Braves.[14] Over 53 games between the two teams, he batted .277/.344/.393 with two home runs and 27 runs batted in.
Due to the cancellation of the 2020 Minor League Baseball season due to COVID-19, he did not play for a team.[15] In 2021, the Braves invited him to their spring training.[16] He spent the 2021 season with the Rome Braves, slashing .294/.362/.436 with seven home runs, 64 runs batted in, and 27 stolen bases.[17] In June, he was selected to play in the All-Star Futures Game.[18][19]
Harris was again invited to spring training by the Braves in 2022.[20][21] He was assigned to the Mississippi Braves to begin the 2022 season, slashing .305/.372/.506 with five home runs, 33 runs batted in, and 11 stolen bases in 43 games before being called up to the major leagues.[22] During the 2022 season, Harris was ranked the 63rd-best prospect in all of Minor League Baseball, and the Braves' best prospect.[23]
Atlanta Braves
On May 28, 2022, Harris was selected to the major league roster, and he made his debut later that day against the Miami Marlins.[24][25] Harris struck out in his first major league at-bat, and later on in the same game, recorded his first hit, a single, and scored his first run.[26] While facing the Arizona Diamondbacks on May 31, Harris drove in his first career run.[27] Harris hit his first career home run against the Washington Nationals on June 13.[28] During the month of June, Harris had a .347/.371/.574 slash line. Of his 35 hits, 13 were extra base hits. He also drove in 16 runs, stole four bases, and won the Rookie of the Month Award.[29][30] On August 17, the Braves and Harris agreed to an eight-year contract extension worth at least $72 million.[31][32][33] As the season continued, Harris, teammate Spencer Strider, and the Braves' later call-up Vaughn Grissom were considered possible National League Rookie of the Year candidates.[34][35][36] Harris was again named Rookie of the Month for August, posting a .337/.400/.590 slash line. Sixteen of his rookie-leading 32 hits during the month were for extra bases.[37][38] In September, Harris was recognized as Rookie of the Month for the third time, having batted .324 with six home runs and 19 RBIs.[39]
On November 14, Harris was named the 2022 National League Rookie of the Year, finishing ahead of teammate Spencer Strider.[40] Harris and Strider were the second pair of Braves to finish first and second for the award, following Craig Kimbrel and Freddie Freeman in 2011.[41] Harris dedicated the award to Marquis Grissom, his youth baseball tutor, with whom he had continued working during the offseasons.[42][43]