The match will be Thaler’s first Wembley appearance as a referee, having had the role of video official and reserve referee in previous finals.
He will be assisted by touch-judges Joe Cobb and Clint Sharrad, while West Yorkshire duo James Child and Richard Silverwood will be the video referees.
The appointment is an early birthday present for Thaler, who will turn 34 the day after the game.
He said: “I first got into refereeing in 1994. It was the week before the Challenge Cup final and I remember thinking how amazing it would be to referee at a stadium like Wembley.
“This is the first time I have been given the refereeing role at a Challenge Cup final. It’s the pinnacle for any referee in sport.
“No matter what game I am working at, from League One through to large events like this, I always approach them in the same professional manner.
“It’s a huge occasion and I’m sure Hull KR and Leeds will put on a great show.”
Thaler added: “I’ve had phone calls from former referees Fred Lindop and John Holdsworth to congratulate me on this appointment.
“Stuart Cummings and Steve Ganson have been brilliant too with their support and guidance.”
More than 79,000 tickets havebeen sold for the final.