Wildcats signed Yates on a contract until the end of next season, shortly before today’s transfer cut-off.
Beating the deadline means he will be eligible for Wildcats’ battle against relegation in the Super League Qualifiers.
The 25-year-old has made 10 substitute appearances for Rhinos this season, plus 10 starts and one appearance off the bench as a dual-registration player for Kingstone Press Championship outfit Hunslet Hawks.
Yates came through St Helens’ academy before joining Hunslet without having made as first team appearance.
He signed for Rhinos ahead of the 2014 season on a two-year deal, but a torn Achilles and then a ruptured biceps tendon restricted him to just one game, for Hunslet, last season.
He said: “I spoke to Brian [Smith, Wildcats’ coach] and Michael [Carter, club chairman] weeks ago and they told me the plans for the club and how they want to stay in Super League and I want to help them.
“I want to try and do my best for the club and show what I can do as a player.”
Carter said, “I’d like to welcome Andy to the club. I am delighted to have signed him on an 18-month contract and I would like to thank Gary Hetherington and Leeds Rhinos for making the move possible. Andy will provide competition for places in our forward pack.”
Wildcats have also brought in Bill Tupou, Lee Smith and Scott Moore this week and Yates is their 10th recruit since Smith was appointed at the end of May.
Meanwhile, Featherstone Rovers’ Samoan international forward Reni Maitua has joined Super League side Salford Red Devils on loan for the rest of the season.
Maitua has scored five tries in 13 Championship appearances for Rovers since arriving in the UK from Australia in April.
He said: “I can’t thank the club enough for allowing me to take up the opportunity at Salford Red Devils.
“It was a big decision to come to England and one I’ve not regretted. Everyone involved with the club, from the board to the fans has been awesome and I’m going to miss Featherstone and have nothing but fond memories of my time here.
“I’m sure the boys will be giving it their best shot in the Kingstone Press Championship Shield and I’ll be keeping an eye on results, that’s for sure.”
Rovers chairman Mark Campbell said: “It has been an absolute pleasure to have Reni at the Club, both on and off the pitch.
“I can’t speak highly enough of him.
“Reni came over here with an ambition to play in the Super-8s and he now has the opportunity to do this with Salford Red Devils.
“I only wish it was with us and I hope all goes well for him.