On December 2, 2020, Carter signed a contract with WWE and was assigned to the WWE Performance Center. On the January 13, 2021 episode of NXT, Carter and his tag team partner Wes Lee debuted under the team name MSK. They defeated Jake Atlas and Isaiah "Swerve" Scott in the first round of the Dusty Rhodes Tag Team Classic tournament, which they would go on to eventually win. At NXT Takeover: Stand and Deliver, MSK defeated Grizzled Young Veterans and Legado Del Fantasma in a triple threat tag team match to win the vacant NXT Tag Team Championship. MSK would have their first successful title defense against the team of Killian Dain and Drake Marverick on the April 13 episode of NXT. At NXT TakeOver: In Your House, MSK would team with NXT North American Champion Bronson Reed to take on Legado Del Fantasma in a winners take all match, where the team of MSK and Reed would be successful. At NXT The Great American Bash, MSK would defeat Tommaso Ciampa and Timothy Thatcher to retain their NXT Tag Team Titles. On the September 8 episode of NXT, MSK would defeat Oney Lorcan and Danny Burch to retain the NXT Tag Team Titles. On the October 5 episode of NXT 2.0, MSK would successfully defend their tag titles in a fatal four-way elimination match. At NXT Halloween Havoc, MSK would lose their titles to Imperium, ending their reign at 201 days. MSK would win the titles for a second time at NXT Stand and Deliver on April 2, 2022, after defeating Imperium in a triple threat tag team match also involving the Creed Brothers. However, on April 6, Carter was released from WWE while reigning NXT Tag Team Champion.
Carter, under the name Zachary Wentz, made his return to NXT on July 9, 2024 alongside Trey Miguel, reuniting with Wes Lee. In his first WWE match since 2022, Wentz, Lee and Miguel defeated Gallus (Joe Coffey, Mark Coffey and Wolfgang) in a six-man tag team match the following week. During week two of The Great American Bash on August 6, Wentz and Lee were defeated by NXT Tag Team Champions Nathan Frazer and Axiom in a title match. After the match, Lee turned on Miguel and Wentz, lashing out at the latter for leaving him back in 2022 to turn heel for the first time in his career. Wentz returned to NXT on August 20 to attack Lee and a match between Wentz and Lee was made official for NXT No Mercy a week later. Wentz would go on to defeat Lee at the event on September 1. Two days later, Miguel and Wentz defeated Gallus (Mark Coffey and Wolfgang) and Hank Walker and Tank Ledger in a triple threat tag team match for an NXT Tag Team Championship opportunity. However, Miguel and Wentz failed to appear for the title match after Lee had taken out Miguel offscreen. Lee then challenged Wentz to a street fight on the October 1 episode of NXT where Lee won.