The German finished on 15-under overall to edge out overnight leader Gonzalo Fernandez-Castano – who finished joint second with Frenchman Raphael Jacquelin.
Kaymer, 24, now goes into the Open at Turnberry, which starts on Thursday, on a hat-trick after compiling winnings of over £1 million in France and Scotland.
“Everyone asks me about the third win in a row,” said Kaymer. “We are playing a major next week. And the field is going to be the best we have all year long.
“After last week and this week, I feel really good, my game is solid, so hopefully, I can keep it up.”
By winning the two events prior to the Open, the 2007 European Tour Rookie of the Year became the first player to do so since Ian Woosnam in 1990.
Meanwhile, two-time US Open champion Retief Goosen dropped six shots between the 7th and the 11th to fall out of contention, and Lee Westwood closed with a 71 to tie for 8th spot with compatriot Ross Fisher.
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