Malone joined Harlequins from Bath in 2007
Australian-born fly-half Chris Malone has signed for London Irish on a two-year deal.
The 31-year-old will join the Exiles for the start of the 2009-10 season after agreeing a move from Harlequins.
"Under the guidance of Toby Booth and Mike Catt I feel there is great belief in the club's prospects for the future," said Malone.
"Their willingness to attack is how I like to play and I hope to bring my skill to an exciting squad."
Head coach Booth added: "In professional rugby today you look for players that have the ability to control a game and the skills execution to do so.
"Chris Malone has demonstrated that he has both in abundance so when the opportunity came to recruit him for our squad, we didn't hesitate to do so."