Striker Samuel Eto'o struck the opener after 10 minutes when he cut in from the right past Nemanja Vidic [ Images ] with surprising ease and his low shot beat United goalkeeper Edwin van der Sar [ Images ] at his near post. Xavi [ Images ] cracked a free kick against a United post at the start of the second half before Lionel Messi [ Images ] sealed the win after 70 minutes when he scored with a beautifully timed header from Xavi's cross.
The win was Barcelona's third in Europe's premier club competition following their earlier successes in 1992 and 2006 and completed a treble after their successes in La Liga [ Images ] and the King's Cup.
"I've been waiting so long to get this title and finally today," Barca striker Thierry Henry [ Images ] told ITV. "The last five minutes were the longest of my life. You never know what can happen -- we were playing against best team in the world.
"It's amazing. All year we played the same way, we wanted to play football. I don't think we started well. We had to play better, then we passed the ball the way we can.
"It's my daughter's birthday today so it's a double celebration."
United, who were attempting to become the first club in the Champions League era to retain the European Cup, dominated the opening 10 minutes of the game but never looked like winning it once Barcelona had taken the lead.
Thierry Henry, Messi and Eto'o all went close to scoring for Barcelona in the second half but those two goals were enough to give coach Pep Guardiola the European Cup in his first season in charge.
Victory for Barca also ended United's record 25-match unbeaten run in the competition and give them their first ever defeat in a European final.