King was officially assigned to NXT in late August 2023 and videos promoting his debut began airing in September. On the October 10 edition of NXT, a vignette aired of King discussing his father, Brian Pillman, and how he was going to take on the last name King, the last name of the real father figure in his life. He competed in his first match on October 24, during night one of NXT Halloween Havoc, defeating Dante Chen. King wrestled his first WWE premium live event on December 9 at NXT Deadline, where he lost to Carmelo Hayes. After the match, King said that he did not attack Trick Williams back in October and thanked Hayes for the spotlight. King would then participate in the 2023 NXT men's Breakout Tournament, but lost to Riley Osborne in the semifinals after interference from Trey Bearhill. On the January 9, 2024 episode of NXT, King would unsuccessfully challenge Dragon Lee for the NXT North American Championship. On the October 15 episode of NXT, King faced Oro Mensah in a Gentleman's Duel match, where he would emerge victorious. After the match, both King and Mensah shook hands, with the former subsequently raising Mensah's hand as a sign of respect.