Born in Irun in the Basque Country, Regueiro started his playing career at Real Unión in 1925.
In 1932 he moved to Real Madrid where he played with his older brother Luis Regueiro.
[5] In 1937 and 1938, during the Spanish Civil War in his homeland, he played for the Basque representative team which toured Europe and the Americas, ending up in Mexico where he initially played for Club Deportivo Euzkadi (The Basque exiles' team) in the Primera Fuerza league for the 1938–39 season.
He then joined Mexican side Club Asturias where he played with his younger brother Tomás Regueiro, and helped the club win the first championship of the newly created Mexican Primera División (1943–44).
[6] In 1939 Regueiro settled in Mexico, where he married Peri Romero in 1943 and had four children: Pedro, Mari Carmen, María Eugenia and José.