The towering second-row, who had reached the end of his contract at Wheldon Road, has signed a two-year deal with the French club.
McMeeken has established himself as one of Super League’s leading back-rows having scored 31 tries in 123 games for Castleford since joining from London Broncos in 2015.
He helped them win the League Leaders’ Shield two years later and also earned a place in the Dream Team as well as a spot in Wayne Bennett’s 2017 World Cup squad.
McMeeken, 26, is Catalans boss Steve McNamara’s first new signing for 2021 and he is looking forward to playing in Perpignan.
“I’m delighted to be joining this great club with such passionate fans,” he said.
“I have played at the Stade Gilbert Brutus a few times now, so I’ve seen what a great atmosphere the fans make.
“It’ll be great to run out in front of them as a home player.
“Steve explained to me that the club wants to recreate the 2018 Challenge Cup success with more silverware and it’s something I definitely want to be a part of.
“Considering the conditions this season, I thought the lads were unlucky not to get further then they did.
“But hopefully we can get some silverware in the coming seasons. I’m looking forward to getting started.”
McNamara added: “Michael is a high-quality signing for the club.
“His sheer size and athleticism combined with his ability to be an 80 minute player make him quite unique and he suits the modern game.
“At the age of 26 he is coming into his prime years.
“I am excited with the qualities that he will bring to the team.”
Castleford are well-served for back-rows with the likes of Oli Holmes, Alex Foster and Jesse Sene-Lefao still on their books and head coach Daryl Powell having already confirmed Australian centre Cheyse Blair will switch to that position in 2021.