The presence of Architectonicidae in Chile was previously recorded only from fossil material of eight species present during the Lower Miocene, when Architectonica karsteni had a geographic range that extended from Costa Rica to central Chile (34 S). No evidence of the presence of the family in Chile after the Lower Miocene have been reported. As part of this study, we report the discovery of A. karsteni at four seamountsat~ 200 m water depth in the recently created Nazca-Desventuradas Marine Park, located~ 900 km west of continental Chile. Morphological identification was based on protoconch diameter, coloration patterns, and teleoconch sculpture. We also provide sequence data for portions of the mitochondrial COI and 16S rRNA genes to contribute to data available for future population-level and phylogenetic analyses of this poorly known group. Insight on the habitat of the species, based on underwater imagery is also provided. This new record extends the geographic distribution of A. karsteni~ 20 southward from its current recorded range (ie, Baja California to Perú). The finding of this species highlights the relevance of gaining knowledge of the fauna inhabiting these seamounts to inform conservation efforts of these relatively pristine habitats.