The pair started Sunday level on 13-under-par and while Molinari carded a flawless 68 to finish at 17 under, McIlroy's 70 left him two shots adrift in second place despite birdies at the last two holes.

"It is disappointing," said Northern Ireland's McIlroy, who won the Wentworth tournament in 2014.

"(Molinari) was like a robot, he doesn't hit it off line. I would have needed a great round to beat him.

"Today I played similar to Saturday, I could not get going and gave Molinari a lead early on. It was a little too late for me in the end."

McIlroy, four-time major champion, wasted a birdie opportunity on the 2nd hole and Molinari birdied the 3rd and 4th to move two clear.

McIlroy dropped shots at the 9th and 10th holes to leave Molinari three ahead and he never looked like losing his lead until the 18th.

McIlroy reacts to a missed eagle putt on the 18th green during the final round of the BMW PGA Championship at Wentworth. PHOTO: Richard Heathcote/Getty Images.

He was close to finding water as McIlroy set up an eagle opportunity but the Italian's ball came to a rest on the fringe and the World No.32 safely made par to claim the title after finishing runner-up last year.

Molinari, 35, continued his fine record at Wentworth, having finished in the top 10 in five of the last six years, and boosted his chances of earning a place in Europe's Ryder Cup team after being on the winning side in 2010 and 2012.

"If I could pick one tournament to win in my career it would be this one," Molinari said.

"The Ryder Cup is very special. It hurts to watch it on TV. You really want to be there. I've been lucky to be on two winning teams and I hope to be able to win a third time."

Denmark's Lucas Bjerregaard, who birdied five holes on the back nine, and defending champion Alex Noren of Sweden finished in a tie for third on 14 under par.