Kagawa joined United this summer from German champions Borussia Dortmund and Rooney has said that he is confident that Kagawa will be able to create plenty of chances for him.
"Shinji's settled quite quickly," Rooney told the club's official website. "He's a talented player, he likes to get on the ball and keep it simple.
"He's very effective on the ball. It's great to have that sort of player in the team. I'm looking forward to playing with him and I think he'll create a lot of chances for myself and the other forwards. It's exciting to have him in the team."
Kagawa played for Dortmund for two years, scoring 21 goals.