Nadal, who has never lost to a fellow Spaniard in a final, kept his perfect record intact by routing reigning three-time champion David Ferrer 6-0 6-2.
Second seed Nadal, who also won this event in 2005, was appearing in his third final of the year. He won in Sao Paulo on February 17 and was runner-up in Vina del Mar, Chile, the previous week.
Nadal needed just 65 minutes to clinch the title, serving brilliantly throughout as he won 81 percent of his first-serve points. He saved both break points he faced.
World number four Ferrer had his serve broken five times.
The women's final was similarly one-sided with Italy's Sara Errani, the top seed, beating Carla Suarez-Navarro of Spain 6-0 6-4.