Paire, a 23-year-old Frenchman, outlasted top-seeded Spaniard Pablo Andujar, 6-3, 1-6, 6-3, firing seven aces while saving five of eight break points in the match.
The world No. 96 will be facing Seppi, who made the final with a 2-6, 6-2, 7-5 triumph over Argentine David Nalbandian, who committed seven double faults en route to the loss.
It will be the first final of 2012 for the Italian.
Swim Week Miami Beach 2014 [PHOTOS]