The 29-year-old winger was part of the squad that took Hull Kingston rovers into the top flight last season, before he was released by the East Yorkshire club.
He has signed a one-year deal at the club where he touched down for a 17-try haul in 2003; a season which ended with the Centurions losing out in the NFP Grand Final to Salford City Reds.
Rivett has also had spells with Leeds Rhinos, Huddersfield Giants, Keighley Cougars, Warrington Wolves, Chorley Lynx, Doncaster Dragons before his move to Craven Park, and has also played rugby union for Otley and Sale Sharks.
"Leroy will bring good experience and good speed." Leigh boss Darren Shaw commented. "He'll give good go-forward and has great feet. He is also very mobile and there is plenty of involvement in him.
“He can cover both fullback and wing and I'm going to look at putting him at fullback for our first game on Boxing Day against Swinton. He gives us great versatility and we have plenty of options now too. We can now rotate a number of positions on either side of the field.
“I'm looking forward to working with him and have been chasing him for a couple of weeks. I'm now very happy that he has signed."