The bird was seen landing in the central concourse of the medium security La Reforma jail, in San Rafael de Alajuela, where it was taken into custody.
The drugs were contained in a small zipped up pouch strapped to the animals chest.
About 14g of cocaine and at least the same amount of cannabis were inside wrapped in plastic.
Costa Rica's Ministry of Justice and Peace released the animal's mugshot under the headline caption "narcopaloma", meaning "drugs dove", and listing the date of the animals detention.