Froome went for the win with 5.5km remaining on the ascent of Col de l'Ospedale and came out on top, finishing 27 seconds ahead of fellow Team Sky rider Porte.
The Australian was leading the overall race, two seconds ahead of Froome, before Sunday's third and final stage but his team-mate overhauled him to claim the victory.
Corsica will host the start of this year's Tour de France at the end of June and last-year's runner-up Froome, who has made it his aim to succeed Bradley Wiggins as Britain's next Tour winner, is in good form so far in 2013.
As well as this latest title, he has already won the Tour of Oman and finished second at the Tirreno-Adriatico this season.
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