The 26-year-old from Munich added a closing two-under 69 to opening rounds of 67, 74 and 65 for a total of nine-under-par 275 at Argentario Golf Resort and Spa on Monte Argentario.
Eberl began the day with a two stroke lead and stalled with an early bogey at the second hole, but bounced back with two tap in birdies at the seventh and eighth holes to claim a three stroke cushion at the turn.
She knocked in a four-foot birdie putt at the par-four 10th hole, before carding another bogey at the 13th hole, where she pulled her tee shot left into deep bushes and took a penalty drop.
After sealing the win and first prize of 67,500 with a tap-in birdie at the par-four 18th hole, she said: Im so happy right now. It was very hard out there and the wind was very difficult all week.
I didnt know I was leading until I hit my second shot into the 18th hole and looked over to the leader board. I ignored every score board all day because it doesnt help me and I figured that out a long time ago.
I must thank my caddie Paul (Vincent Fernie) because he was calming me down all day. He knew I didnt want to know the scores and without his help I wouldnt have won. I never want to give him away.
Eberl said she would celebrate in a local restaurant with some pasta and her boyfriend Thad Kael (Kiran Matharus current caddie) before heading to the Evian Masters, from July 24-27.
The next two weeks are European majors but I just want to enjoy this week first, said Eberl, adding: Im looking forward to next week and I hope that I can play well again there.
The US$3.25 million Evian Masters is considered a major on the Ladies European Tour and the prize money is the highest in womens golf alongside the Womens US Open.
Spains Carmen Alonso had a career best finish of second after shooting 66 and playing the back nine in six-under-par.
Alonso, who has limited playing privileges on tour this year, entered the tournament as the first reserve and with her fine performance almost certainly secured her car d for the 2009 season.
The longest hitter on the Ladies European Tour fired five birdies in a row from the 10th hole, with another at the 16th, for an inward total of 29 strokes.
She explained: Two months ago I was practising at my home club, Race Golf Club in Madrid, and I made six under on the back nine. I was standing on the 10th tee today and I thought, Why not six under on the back nine today? It could have been seven birdies in a row because on 15 I made a really good birdie putt but missed it by an inch.
I was two over after seven holes but the best thing I have learned from Laurette Maritz is that you have to fight until the end. Thats it.
Im so happy because my mum is here and all my problems have gone away. Now I can relax. I just wanted to keep my card. Of course I am happy about the money but for me money is not the20most important thing. I need to have my card because with my card I can play and for me that is everything. Golf is my passion.
Denmarks Lisa Holm Sorensen shot a final round 73 and shared third on three-under with World No 11 Maria Hjorth from Sweden and Wales Becky Brewerton, who both shot 72.
The leading Italian player was Stefania Croce, who shared sixth with three others: Swedens Christine Hallstrom and the French duo of Gwladys Nocera and Anne-Lise Caudal.