The 24-year-old has played the last four seasons with NRL club Manly Sea Eagles and will join the Broncos - soon to be called Harlequins Rugby League, in time for the start of the 2006 season.
"He's a very natural footballer who reads the game very well," said coach Tony Rea.
"I think he will form a solid combination with our halves and also work well with Neil Budworth."
Budworth, who missed the entire 2005 season after undergoing a knee reconstruction, recently agreed to a contract extension which will keep him in London until at least the end of the 2006 season.
Meanwhile, the Broncos have confirmed the departure of eight players from this year's squad.
They are Francis Stephenson, Steve Trindall, Anthony Armour, Dave Highton, Mark O'Halloran, John Kirkpatrick, Lee Sanderson and Feleti Mateo.