Robin van Persie scored a first-half hat-trick to secure the win, and Rooney has had to take a back seat to the Dutch striker at times this season, leading to speculation over his future at the club.
However, Rooney insists that winning the title was all that mattered for him and believes that Sir Alex Ferguson's winning mentality rubbed off on the side having missed out on the title in the closing minutes of last season.
"We won this game in the first half and it is a fantastic night for us. When you lose the title, it is hard to take. It wasn't a nice feeling last time. We have all dug in deep and done fantastic to put ourselves in this position," said Rooney.
"You can never take anything for granted in football and thankfully it is now done. The manager has great desire and a winning mentality. We all buy into that and want to do well for the club.
"It has been a great season for me. We have won the league title, that is what you play for."
The title is Manchester United's 20th league crown in their history, making them the most successful English club of all time.