Avellaneda is a city in eastern Argentina, a port in Buenos Aires Province, and capital of Avellaneda District. Its population in 1991 was 344,991.

Avellaneda is a suburb of the city of Buenos Aires and is connected to it by several bridges over the Riachuelo River . A major rail center, Avellaneda is also one of the foremost commercial and industrial centers of Argentina. It contains textile mills, meat-packing and grain-processing plants, oil refineries, metallurgical works, extensive docking facilities, and markets for farm and ranch products.

The city was formerly known as Barracas al Sur; it was renamed in 1904 for the Argentine statesman Nicolás Avellaneda.