The town was founded in 1322 by Dona Maria Diaz de Haro “The good lady” on a settlement that had already been documented centuries earlier and was inhabited by seafaring folk living in the shelter of its natural harbour.

The foundation whose Town Charcher was signed by Dona María, lost years later, was ratified in 1432, with the Privilege of Confirmation by John II of Castile, this document has arrived at our days. In both documents a series of benefits were granted to the people of Portugalete regarding the commerce and merchandise transport, mainly wool and iron, as well as on the fishing activity.

In the 19th century, the industrialization of the region energized its economy, reinforced by the arrival of the railroad and the construction of the Hanging Bridge (Puente Colgante) and the Iron Wharf (Muelle de Hierro). Its situation on the coast, joined to its beach and resort, turned it into the summer residence for the new bourgeoisie, building palaces at the edge of the estuary and on the coast. Throughout the 20th century Portugalete continued being a neuralgic center, commercial area and leisure centre for the left bank of the river.