Third-round leader Simon Dyson began the final round with a four-stroke cushion over Molinari, but then collapsed, bogeying three out of four holes from the fifth. He struggled to a 4-over 76 and fell into a tie for 12th at 1-under 287.
Molinari, meanwhile, finished at 8-under 280. He birdied the ninth hole and claimed sole possession of the lead with a 10-foot birdie putt at No. 10, going on to claim his third European Tour title.
Sharing second place at 5-under 283 were Alejandro Canizares (69), Soren Kjeldsen (71) and Pablo Larrazabal (71).
Knotted in fifth at minus-3 were Thorbjorn Olesen (70) and Jorge Campillo (72).