The hulking prop forward, renowned for his explosive style of play, will link up with his new teammates in London next week on a two-year deal.
Richard will link up with former Warriors' team-mate and prop forward, Karl Temata.
Quins RL head Coach Brian McDermott is delighted to add more firepower up front: "Richard will add immense strength and experience to what is already a very competent pack of forwards."
"He is just the type of player we have been looking for and I am delighted he is joining us."
"We will be continuing to bolster the squad with the right calibre of person, but as I have stated many times, it must be the right person."
Richard began playing rugby league at the age of ten, starting out in the round ball game.
Harlequins RL v Salford City Reds, 6pm Saturday 17th February, Twickenham Stoop
Supporters can still purchase a 2007 Quins RL Season Ticket from just £99!
Book match tickets to the first home game from just £12 either online or on the phone 020 8410 6000.