He compiled the bibliographic section of the Enciclopedia general ilustrada del País Vasco (1970), and the monumental Eusko-bibliographia: diccionario de bibliografía vasca (10 volumes, 1970–1981, with further supplements), which has been described as "one of the most significant reference works on Basque studies".
Between 1932 and 1936 he attended the Universidad Central de Madrid, pursuing studies in Philosophy and Literature, specializing in History.
He spent many hours in Boston Public Library, sifting through dictionaries, encyclopedias and biographies to fill the filecards that were eventually to form the basis of his monumental Bibliografia Eusko, a standard work of reference in Basque studies.
In this capacity he was sent on a study and fund-raising trip to Boise (Idaho) in 1940, wrote in support of the Basque cause with M. de la Sota and A. Irala, and worked with the Belgian Office for Latin America as associate editor of the Journal Belge (1944) and Ambos Mundos (1945–46).
His activities in Basque-Belgian co-operation during the struggle against fascism led to him being made a Knight of the Belgian Order of the Crown after the end of the Second World War.
Barandiaran as editorial secretary to Eusko Jakintza (Spanish title Revista de Estudios Vascos).
Leaving his family in Getxo, he went to live in Biarritz, but after a year was expelled as an undesirable alien by the French police.
Continuing to work on his monumental bibliography, Jon Bilbao taught Spanish at Georgetown University in 1964–1965, and at the Naval Academy in Annapolis (Maryland) in 1966–1968.
In 1970 he was appointed director of the "Basque Studies Summer Courses", in the decade 1970-1980 was organized five in Ustaritz, Arantzazu Loiola, Vitoria-Gasteiz and Oñate.
Moreover, in 1987 founded the "Harrilucea Association for the Study of History" with a desire to open a museum and a library in Getxo.
On March 30, 1994, J. Bilbao suffered the first stroke while working in Vitoria and was admitted to the Sanatorium Gorliz in a rehabilitation program.