The 34-year-old, who is the Super League's record try-scorer, will head to Craven Park for the start of the 2018 season.
The former Great Britain half-back has had a glittering career so far, winning seven Grand Finals with Leeds, two Challenge Cups, three World Club Challenge titles and three League Leaders Shield crowns.
"I could have quite easily stuck around at Leeds and finished my career here, but I feel like I've still got a lot to give and that I'm still playing well, so I'm looking forward to starting afresh and putting a marker down at Hull KR. Hopefully, we can have a good season and create some good times there," McGuire told Hull KR's official website.
"I had a couple of options but once I'd spoken to Jamie Peacock and Tim Sheens, I made my mind up pretty quickly. With the direction the club is wanting to go and having the chance to work with somebody with Tim's experience and everything he's achieved in the game, it seemed the perfect fit. I know quite a few of the boys there already, the ex-Leeds lads and people like Shaun Lunt, so everything just felt right.
"The main thing I want to let everybody know is that I'm coming over there to play well. I still feel like I'm playing well individually and I've got plenty of experience to add to the team. I'm not coming just to rest on my laurels and have a holiday, I want to be part of a successful team at Rovers.
"It's an exciting challenge for me because I'll basically be coming across having to prove myself all over again to everybody, not just my new teammates and my new coaches, but to the club and the fans."
Hull KR were relegated from the Super League in 2016.