Alonsotegi is a municipality in the province of Biscay, Basque Country, Spain. Alonsotegi was attached to the Baracaldo municipality until the end of the 19th century, when it separated and was officially recognized as its own independent municipality. Alonsotegi is approximately 8 kilometres from the center of Bilbao. It is located in the valley of the Cadagua River, following Highway BI-636.