Born in Sassari, in his youth he was a follower of the Meridionalist activist Gaetano Salvemini. After his graduation in law he collaborated with the newspaper La Nuova Sardegna and other Italian newspapers.
He was elected to the Italian Chamber of Deputies in 1924. The following year he founded the clandestine newspaper Sardegna libera ("Free Sardinia") which attracted him the hostility of the Fascist regime. After the armistice with Italy (September 1943), he joined the Action Party. For the latter Berlinguer was a member of the second government formed by Pietro Badoglio in southern Italy.
In 1945 he was named to the Consulta Nazionale and collaborated to the elaboration of the special regional status for Sardinia. He was a deputy for PSI from 1948 to 1953.