Eoin Reddan continues his half-back partnership with Jonathan Sexton, with Ireland duo Luke Fitzgerald and Shane Horgan starting on the wings and Isa Nacewa lining up again at full-back.
In the pack, Ross comes into the front row alongside Cian Healy and John Fogarty with skipper Leo Cullen, one of 13 Ireland-qualified players in the starting side, linking up in the second row with Scotland international Nathan Hines.
CJ van der Linde has been included in the matchday squad for the first time this season. The big South African prop joins Bernard Jackman and Ronan McCormack as one of the three front row replacements.
Friday's game is a sell out and tickets will not be available on the day.
LEINSTER (v London Irish): Isa Nacewa; Shane Horgan, Brian O'Driscoll, Gordon D'Arcy, Luke Fitzgerald; Jonathan Sexton, Eoin Reddan; Cian Healy, John Fogarty, Mike Ross, Leo Cullen (capt), Nathan Hines, Kevin McLaughlin, Shane Jennings, Jamie Heaslip.
Replacements: Bernard Jackman, Ronan McCormack, CJ van der Linde, Malcolm O'Kelly, Sean O'Brien, Simon Keogh, Shaun Berne, Rob Kearney.