It took two hours, but Almagro outlasted Volandri 6-3, 4-6, 6-4 to take his third overall Brazilian crown.
He also won the event in 2008 when it was held at Costa do Sauipe.
The 26-year-old Spaniard amassed 18 aces in the triumph, the 11th of his career.
Volandri, 30, was appearing in his first final since 2006.
Swim Week Miami Beach 2014 [PHOTOS]