The striker admits that watching Manchester City pip his side to the title on goal difference was "difficult" but is already looking forward to next season
Sir Alex Ferguson's men looked on course to claim yet another title after beating Sunderland 1-0, however, a dramatic last-gasp goal from Sergio Aguero sealed a 3-2 win over QPR and the crown for the 'noisy neighbours'.
Rooney can not hide the fact that the way in which the title was decided was hard to take as a United player.
"Sunday was a difficult day for everyone," the England international told reporters.
"One minute you think we have won the title, then we haven’t, which was heartbreaking."
And in what was perhaps the most memorable Premier League season ever in its 20 year history, the pendulum swung to the blue side of Manchester merely on the merit of superior goal difference.
But Rooney stated that the way in which United let their lead slip against his former side Everton in April was a pivotal moment in the race for the title.
"The biggest disappointment was the Everton game. To be 4-2 up — with 10 minutes to go — and to lose that lead is hugely disappointing," he said.
"But there are a lot of young players in the team. That is only going to benefit them. They will learn from that.”
Many believe that the title for City could be the beginning of domestic and European dominance for Roberto Mancini's side, given their seemingly never ending transfer funds.
But Rooney is determined to not let that happen and remains optimistic over United's success next season.
"We have to look forward to next season and hopefully we can win some trophies," said Rooney, who has netted 27 times in the Premier League this season.
"I am sure we will be back. We all believe in ourselves."