Two-time defending champion and No. 1 seed Ferrer made the final with a 6-4, 6-2 cruise over fellow Spaniard and 2011 winner Nicolas Almagro at Buenos Aires Lawn Tennis Club.
Alamgro fell to 0-15 lifetime against Ferrer with the defeat.
The second-seeded Fognini continued his recent clay-court dominance with a comeback win over third-seed Tommy Robredo 3-6, 7-5, 6-3.
The Italian improved to 23-1 on the surface stretching back to the 2013 French Open.
Ferrer owns a 6-0 career record against Fognini.