New Zealander Fox started the final round four shots behind but made seven birdies and three bogeys to finish with a four-under 68 and 15-under for the tournament, one better than Callum Shinkwin and Alex Noren.
Fox had partnered with amateur Warne last year to finish second in the pro-am team event. The Australian spin-bowling great died aged 52 of a suspected heart attack while on holiday in Thailand in March.
"To be honest the only person I can really think of at the moment is Warney," Fox said after his win.
"He meant a lot to me and this event and was a great mate. It's a terrible shame he's not here."
The win was Fox's third title on the European DP World Tour, adding to his victory at the Ras Al Khaimah Classic in February and his World Super 6 crown from 2019.
When asked if he felt Warne's presence on the course, Fox said, "Yeah, there was definitely some luck out there.
"Obviously I was pretty nervy the last three holes. I didn't hit very good shots, to be honest, down the 16th, 17th and 18th. He was definitely helping out."
Rory McIlroy carded a six-under 66 to end tied for fourth.
