Llay-Llay is a town and commune in the San Felipe de Aconcagua Province of central Chile's Valparaíso Region.

The commune was established on 6 April 1875 during the government of President Federico Errázuriz Zañartu, A railway station was initially built for the three copper smelters that existed there.

[2] As a commune, Llay-Llay is a third-level administrative division of Chile, administered by a communal council (consejo comunal), which is headed by a directly elected alcalde.

The communal council has the following members:[1] Within the electoral divisions of Chile, Llaillay is represented in the Chamber of Deputies by Marco Antonio Núñez (PDC) and Gaspar Rivas (RN) as part of the 11th electoral district, together with Los Andes, San Esteban, Calle Larga, Rinconada, San Felipe, Putaendo, Santa María, Panquehue and Catemu.

The commune is represented in the Senate by Ignacio Walker Prieto (PDC) and Lily Pérez San Martín (RN) as part of the 5th senatorial constituency (Valparaíso-Cordillera).