Barroso's political activity began in his late teens, during the Estado Novo regime in Portugal, before the Carnation Revolution of 25 April 1974. In his university days, he was one of the leaders of the underground Maoist MRPP (Re-Organized Movement of the Proletariat Party, later Portuguese Workers' Communist Party (PCTP/MRPP), Communist Party of the Portuguese Workers/Revolutionary Movement of the Portuguese Proletariat). In an interview with the newspaper Expresso, he said that he had joined MRPP to fight the only other student body movement, also underground, which was controlled by the Portuguese Communist Party. Despite this justification, there is a very famous political 1976 interview recorded by the Portuguese state-run television channel, RTP, in which Barroso, as a politically minded student during the post-Carnation Revolution turmoil known as PREC, criticises the bourgeois education system which "throws students against workers and workers against students." In December 1980, Barroso joined the right-of-centre PPD (Democratic Popular Party, later PPD/PSD-Social Democratic Party), where he remains to the present day.
Barroso is the son of Luís António Saraiva Barroso and his wife Maria Elisabete de Freitas Durão. In 1980 he married Maria Margarida Pinto Ribeiro de Sousa Uva, with whom he has three sons. Sousa Uva died from uterine cancer in August 2016, at the age of 60.