Former champion jockey Ryan Moore will be the senior rider for Aidan O'Brien's Coolmore operation this season.
O'Brien's son Joseph, who has been battling to overcome weight difficulties, will continue to ride for the Ballydoyle stable.
Aidan O'Brien said: "Ryan will be riding our main horses this year and Joseph will be riding other horses when the weights allow him to.
"Seamie Heffernan and Colm O'Donoghue will also be involved as in the past."
Joseph O'Brien was Irish champion jockey in 2012. His father added: "I'd imagine that if he wants to, Joseph will continue to ride over hurdles."
Moore has ridden for O'Brien many times in the past and will partner Investec Derby favourite John F Kennedy at Leopardstown on Sunday.