The Portugal international was linked with a move away from the Premier League champions following reported interest from Roma, Juventus, Paris Saint-Germain and Monaco.
Despite suggestions that United were open to offloading the 26-year-old, it has been confirmed by the North-West outfit that Nani is part of new manager David Moyes's plans.
"Playing at United has been a fantastic experience for me," Nani told the club's official website. "When I came to the club, I never imagined the success we have enjoyed."
Nani, who was controversially sent off in last season's defeat to Real Madrid in the knockout rounds of the Champions League, moved to the Premier League outfit from Sporting Lisbon in 2007.