Italy's Fognini breezed to a 6-2, 6-4 victory over the unseeded Mayer on the clay court at Vina del Mar, improving to 3-3 all-time in championship matches.
Fognini also made quick work of the Argentine in their only other previous match, winning in straight sets last year in Stuttgart.
Mayer fell in his first career final appearance.
Notable deaths of 2014 [PHOTOS]
Arizona Cardinals player formally charged