Donaldson carded five birdies to overcome a pair of bogies on the back nine, ending at 18-under 270 -- four shots better than a trio of competitors.
The Welshman was a three-time Challenge Tour titlist and twice claimed runner-up status on the European Tour before Sunday's victory.
Sharing second place at 14-under 274 were Anthony Wall (69), Rafa Cabrera-Bello (66) and Fabrizio Zanotti (66).
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