Ferrer defeated fellow Spaniard Nicolas Almagro, the 2011 champion, 6-4, 6-2 in the semifinals on Saturday. Ferrer has won 20 ATP events, including the last two in Buenos Aires.
Fognini defeated Tommy Robredo of Spain 3-6, 7-5, 6-3, coming back from 6-3, 5-3 to oust the 2009 champ.
Fognini won the ATP event last week in Chile, picking up his third singles title.
He has reached the final in a fifth consecutive clay-court event since the French Open.