The 37-year-old terminated a three-under 69 in the last round at Diamond Country Club in Austria to complete on 16 under 272 and stay well clear of closest challenger Connor Syme.
Steve Webster, Nicolas Colsaerts, Raphael Jacquelin and Justin Walters shared third spot on nine under, with David Horsey part of the gathering a further stroke back.
Korhonen saw his five-shot medium-term lead slice to four when he had jump started after Jacquelin birdied three of his opening six gaps, just for the Finn to reestablish his favorable position by getting a shot at the third.
Walters climbed the leaderboard with four straight picks up from the fourth, as Korhonen holed a 12-footer at the fifth and coordinated the South African’s birdie-two at the 6th.
Walters twofold came up short the eighth to enable Korhonen to intruder the ninth and still turn with a six-stroke pad, before skipping back to birdie the following and increment his preference further.
The last round was ended for a moment time because of the danger of lightning, with Korhonen neglecting to get here and there from a dugout to spare standard at the twelfth when play continued 40 minutes after the fact.
Korhonen reacted to prod in a short proximity birdie at the thirteenth and finished off his triumphant round with a keep running of standards, as Scotland’s Syme depleted a 60-footer at the last to snatch inside and out second.
Felipe Aguilar required 15 shots to finish the standard five sixteenth and was later excluded for neglecting to sign for the correct scorecard, while Markus Brier and Oscar Stark both got one-shot punishments for rupturing time rules.