The Castilletes Formation (Spanish: Formación Castilletes, N1c) is a fossiliferous geological formation of the Cocinetas Basin in the northernmost department of La Guajira, Colombia.

The Castilletes Formation dates to the Neogene period; Burdigalian to Langhian stages, Colloncuran and Friasian in the SALMA classification, and has a maximum thickness of 440 metres (1,440 ft).

The formation was defined by Rollins in 1965 and named after the village of Castilletes.

The age has been estimated to be Middle Miocene (16.7 to 14.2 Ma), Colloncuran and Friasian in the SALMA classification.

This unit is also correlative with the Cantaure Formation of the Paraguaná Peninsula in Venezuela.