Only a rain break during the fifth game could interrupt the Spaniard's march to the first set with Frenchman Monfils taking until the second game of the second set to hold serve.
Montanes, ranked 82nd in the world, did not have it all his own way as Monfils, a former top-10 player who has slipped out of the top 100 after injury, broke in the seventh game of the second set and then held to level at four games apiece.
The pair then kept pace with each other to take it into a tiebreak where Montanes triumphed 7-3 to wrap the match up in 73 minutes.
It was Montanes' first title in nearly three years after his triumph on the clay of Stuttgart in 2010, when he also beat Monfils in the final.
Montanes now holds a commanding 4-1 head-to-head record over the Frenchman, who suffered a comprehensive defeat in what was his 18th final on the men’s tour in a setback to his French Open preparations.
Monfils, a French Open semi-finalist in 2008 who has been awarded a wildcard this year, faces fifth seed Tomas Berdych of Czech Republic in the first round at Roland Garros next week, while Montanes has been drawn against a qualifier.
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