Charlotte Hornets (2019–2025)
Martin was selected 36th overall in the 2019 NBA draft by his hometown team, the Charlotte Hornets. On July 31, 2019, Martin signed with the Hornets. On October 25, 2019, Martin made his NBA debut, coming off from bench in a 99–121 loss to the Minnesota Timberwolves with four points, four rebounds, an assist and a steal. On November 29, 2019, Martin received his first assignment to the Hornets' NBA G League affiliate, the Greensboro Swarm. On February 13, 2020, he scored a season-high 13 points, alongside eight rebounds, three assists and three steals, in a 100–112 loss to the Orlando Magic. Martin again scored 13 points, alongside five rebounds, four assists and two steals, in a 103–104 loss to the San Antonio Spurs.
On April 25, 2021, Martin recorded a season-high 13 points, alongside ten rebounds, five assists and two blocks, in a 125–104 win over the Boston Celtics.
On December 15, 2021, Martin scored a career-high 21 points, alongside eight rebounds and three assists, in a 131–115 win over the San Antonio Spurs.
On July 2, 2022, Martin re-signed with the Hornets on a four-year, $32 million contract. He missed four out of the Hornets' five preseason games with left knee tendiopathy. During the Hornets' season-opening 129–102 win over the San Antonio Spurs on October 19, Martin only played 56 seconds before injuring his left quad and exiting the game. On November 11, he underwent an arthroscopic procedure on his left knee and was set to be re-evaluated in four weeks. Martin made his return to the lineup on January 4, 2023, recording four points, four rebounds and two assists in a 131–107 loss to the Memphis Grizzlies.