The 21-year-old Rios, seeded seventh, beat Corretja 6-4, 6-3, 6-3 for the most impressive victory of his career. Rios has won four previous ATP Tour events but none as important as the $2.3m (pounds 1.5m) clay-court tournament in the home town of the super rich.
"I played well and had a great time in Monte Carlo all week - even if I lost some money at the casino," he said.
As well as defeating Corretja, winner in Estoril two weeks ago, Rios had earlier disposed of Spain's Albert Costa, winner of the European season's second clay-court tournament in Barcelona last week.
A semi-finalist here last year, Rios confirmed he would again be one of the players to watch on the slow surface after a lacklustre hard-court season in which he reached only one final, in Marseilles two months ago.
A versatile player, as comfortable at the baseline as at the net, the Chilean mastered the windy conditions far better than Corretja, seeded 12th, who looked tired and made an unusual amount of unforced errors. The most strongly contested game was the last in which Corretja, refusing to bow, saved four match points.
Rios' task had been made easier by the early exit of the top seeds, Pete Sampras, Thomas Muster and Yevgeny Kafelnikov, but he will now fancy his chances in next month's French Open.
n South Africa's Amanda Coetzer beat Sabine Appelmans, of Belgium, in straight sets in the final of the Budapest Open women's tournament yesterday. The second-seeded Coetzer played a consistent baseline game to win 6-1, 6-3 in an hour and seven minutes.Reuse content