Matt Riddle's NXT debut was on the October 31 edition when he successfully defeated Luke Menzies. On November 17, 2018 on the Pre-show of NXT TakeOver: WarGames II, Kassius Ohno interrupted a Riddle interview. When NXT TakeOver: WarGames II started, Riddle challenged Ohno to a match and knocked him out in 6 seconds, winning the fastest match in NXT history.
Riddle and Ohno had a rematch at NXT TakeOver: Phoenix, where Riddle made Ohno tap out to an Arm Trap. In 2019, WWE Network released a documentary on his wrestling career and entry into NXT entitled Arrival: Matt Riddle. Throughout March, Riddle would start a feud with the NXT North American Champion, Velveteen Dream.
On April 5, at NXT TakeOver: New York, Riddle challenged Velveteen Dream for the NXT North American Championship. However, he would defeat Riddle ending his undefeated streak in NXT. In July, Riddle started a feud with the returning Killain Dain.
On the August 7 episode of NXT, Riddle was supposed to face Dain but it never happened since they brawled before the match happened. The two brawled at NXT Takeover: Toronto and eventually faces each other on the August 21 episode of NXT where Dain was victorious but Riddle attacked Dain after the match.
In a long interview with Sportskeeda, Riddle talked about AEW: “I wish them all the best. I’m super-stoked, it’s the Wednesday night wars. And I hope they push the envelope, I hope they push it hard, and I hope they get a lot of fans.
And I hope they’re very successful. Because the more successful they are, the more successful we’ll be. It really helps people out like me if there’s good competition. It helps the performers. The people who actually make the show go, it really helps them."