Four vertebrae of a plesiosaur were recovered from the Katterfeld Formation of the Aysén Basin, north of Lago General Carrera, in the Patagonian Cordillera of Chile. Plesiosaur-bearing strata have been assigned to the Hauterivian based on ammonoid biostratigraphy, in particular they are inferred to be within the “Aegocrioceras and Crioceratites zone, of late early–early late Hauterivian age, above the Favrella Americana and below the “Favrella” wilckensis zones of previous authors. The preserved elements share anatomical characteristics with elasmosaurids, Muraenosaurus leedsii and an indeterminate plesiosaur of the Agrio Formation. However, more complete material is required to elucidate the affinity of plesiosaur present in the Katterfeld Formation. This finding represents the southernmost record of plesiosaurs in the Lower Cretaceous and the first record in the Hauterivian of Chile.