Newman succeeded Alex Mejia as the Wildcats' starting shortstop as a freshman.[2] In his freshman year, Newman had a .336 batting average, the 11th best in the Pac-12 Conference (Pac-12). He was named to the Freshman All-America team by Louisville Slugger,[3][4] and was the only freshman named to the All-Pac-12 Conference team.[5] He had a .304 batting average as a sophomore, and was again named to the Pac-12's All-Conference team.[6] He was added to the Golden Spikes Award watch list before his junior year.[7] Newman also played summer collegiate baseball for the Falmouth Commodores of the Cape Cod Baseball League (CCBL) in the summers of 2013 and 2014, winning the league's batting average title in both years, and the league MVP award in 2014.[8][9][10] He was named to the CCBL Hall of Fame in 2020.[11] In 2015, Newman was named to the All-Pac-12 Conference team.[12]
MLB.com ranked Newman as Pittsburgh's seventh-best prospect going into the 2018 season.[19] He played 102 games for Indianapolis, batting .302, before the Pirates promoted him to the major leagues on August 16.[20]
On April 6, 2019, Newman hit his first walk-off, a single to help the Pirates defeat the Cincinnati Reds 6–5 in 10 innings. In 2019 he batted .308/.353/.446, tied for the National League lead in infield hits (22), and led the NL in at bats per strikeout (8.0).[21]
In 2020 for Pittsburgh, Newman slashed .224/.281/.276 with 1 home run and 10 RBIs.[22] In 2021 he batted .226/.265/.309, and had the lowest OPS in the major leagues, at .574. However, he also led the major leagues in at bats per strikeout (12.6).
Newman began the 2022 season on the injured list with a groin injury, and was placed on the 60-day injured list on May 23 after suffering a hamstring-related setback while rehabbing with Triple-A Indianapolis.[23] He was activated on July 8.[24]
Cincinnati Reds
On November 18, 2022, the Pirates traded Newman to the Cincinnati Reds in exchange for Dauri Moreta.[25] In 74 games for Cincinnati, he batted .253/.311/.364 with 3 home runs, 28 RBI, and 8 stolen bases.[26] On August 19, 2023, Newman was placed on the injured list with a left oblique strain.[27] On September 25, Newman was activated from the injured list and subsequently designated for assignment.[28] He was released by the Reds organization on September 27.[29]
Arizona Diamondbacks
On January 3, 2024, Newman signed a minor league contract with the Arizona Diamondbacks.[30][31] On March 27, Newman opted out of his contract and became a free agent.[32] The next day, he re–signed with the Diamondbacks on a new minor league contract.[33] On April 7, Newman was selected to the major league roster following an injury to Geraldo Perdomo.[34]