Rooney admits Van Persie's presence in the United dressing room has given everyone a lift.
"Obviously it is great for the team - for the players and fans - to sign a player of his quality," he said.
"As forwards it is great for us to have someone like that to play with and it is always exciting when you sign a new player of that quality and ability.
"It also provides strong competition.
"We are all fighting for one or two places, which is good for the team as a whole."