San Bernardo del Tuyú is a city in the seaside La Costa District of the Province of Buenos Aires, Argentina.

Founded by the Compañía Inmobiliara del Este Argentino S.R.L., a partnership of ten investors led by Juan Carlos Chiozza, San Bernardo del Tuyú originated with the 1942 purchase of 191 hectares (480 acres) along the Atlantic Ocean shore from the San Bernardo ranch, one of the Duhau family's many properties in Buenos Aires Province.

The largely self-sufficient settlement initially grew with investments from both the developer and its residents, who pooled resources and established local electric and telephone cooperatives.

Closely linked to Mar de Ajó, San Bernardo slowly grew as a tourist destination, and one of five piers in the district was built along its shores.

One of its early visitors, Uruguayan Argentine poet Juan Burghi, dedicated a poem, San Bernardo, to the seaside hamlet in 1957.