The Italian entered the day in a share of the lead with 2014 champion Rory McIlroy but hit the front on his own with a birdie on the third and never looked back, signing for a 68 and a 17 under par total.
Molinari had finished in the top ten at this event in five of the last six seasons – including a second place last year – and his fifth European Tour victory takes him alongside Costantino Rocca as the most prolific Italian winners in Tour history.
The triumph also represents a third top ten in six Rolex Series events heading into next week’s Italian Open – an event he has won twice.
“It’s amazing,” said Molinari. “I’ve been close so many times. If I could pick one tournament to win in my career it would be this one so to finally get over the line was amazing. I can’t wait to be back next year.
“I knew it wasn’t going to be easy with Rory today, he probably didn’t play his best but I still knew he was going to charge back the last few holes.
“I came into this week knowing that I was a long way back in the Ryder Cup and that something pretty special needed to happen. We are halfway there and next week is another important week from that point of view and hopefully another successful week for me.”
Molinari hit a wonderful approach into the third and holed an eight-footer for birdie, with another excellent approach into the par five eighth bringing another birdie.
Dialled-in iron play had been the trademark of the 35 year old’s play all week and another sensational second brought a birdie from close range on the eighth and a three-shot lead at the turn.
A smart up and down from the front of the par five 12th brought a fourth birdie of the day and the lead was four, with Molinari playing a smart, risk-free final six holes to ease to victory.
Bjerregaard cut the gap to three with a wonderful closing 65 that equalled the lowest round of the week and handed him a third consecutive top ten.
The 26 year old started with a bogey but responded with a hat-trick of birdies and made four in a row from the tenth before adding another on the 17th.
McIlroy scrambled well to stay level par in the early stages and got the biggest cheer of the day when he holed a 20-footer for birdie on the eighth.
The Northern Irishman could not follow that up, however, and back-to-back bogeys on the ninth and tenth dropped him back before he recovered with birdies on the par five 12th, 17th and 18th to leapfrog Bjerregaard.
Noren finished with a course-record 62 last season for victory and it looked like he might be the man to make a charge again as he birdied the third, fourth, seventh, tenth and 12th.
A bogey on the 13th then halted his momentum before he took advantage of the last.
Thai Kiradech Aphibarnrat made an eagle from long range on the fourth and birdied four of his last six holes in a 67 that moved him to 13 under alongside South African Branden Grace, who recovered from a bogey on the third with gains on the fifth, tenth, 11th, 14th and 17th.
Grace’s countryman Darren Fichardt finished with four birdies to get to 12 under, two shots clear of Spaniard Rafa Cabrera Bello, English pair Ross Fisher and Matthew Fitzpatrick, and Thai Thongchai Jaidee.