It was Ferrer's ninth successive victory over Almagro and ended his fellow Spaniard's 10-match win streak.
Ferrer is the second two-time winner on the ATP World Tour this season, joining Milos Raonic.
The 29-year-old world number five began his year by repeating as champion at Auckland.
Almagro was aiming to win back-to-back titles during the Golden Swing in South America for the second year in a row, having successfully defended his Brazil Open in Sao Paulo last week
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