The 26-year-old from Paris carded a final round three-under 70 in hot and breezy conditions to end on a three-round total of 212, seven under par for the par-73 course.
Denmark's Malene Jorgensen finished second with a five-under 214 after a closing 73 , and Laing, who had been second overnight, carded a three-over 76 to finish joint-fourth with Russian Maria Balikoeva, who had a 72. They both earned €12,050.
The Scot was three over par for her last 13 holes. She had a double-bogey 6 at the sixth, birdied the eight, but then had bogeys at the 10th and 16th.
Next best after Laing in the tartan contingent came Sally Watson and Kylie Walker, who tied for 22nd place on 222, Watson with rounds of 74, 72 and 76; Walker 76, 70 and 76. They both earned €2,812.