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.

In 1985, under the PSD government of Aníbal Cavaco Silva, 113th Prime Minister of Portugal, Barroso was named Under-Secretary of State in the Ministry of Home Affairs. In 1987 he became a member of the same government as he was elevated to Secretary of State for Foreign Affairs and Cooperation (answering to the Minister of Foreign Affairs), a post he was to hold for the next five years. In this capacity, he was the driving force behind the Bicesse Accords of 1990, which led to a temporary armistice in the Angolan Civil War between the ruling MPLA and the opposition UNITA. He also supported independence for East Timor, a former Portuguese colony, then a province of Indonesia by force. In 1992, Barroso was promoted to the post of Minister of Foreign Affairs, and served in this capacity until the defeat of the PSD in the 1995 general election.

While in opposition, Barroso was elected to the Assembly of the Republic in 1995 as a representative for Lisbon. There, he became chairman of the Foreign Affairs Committee. In 1999 he was elected president of his political party, PSD, succeeding Marcelo Rebelo de Sousa (a professor of law), and thus became Leader of the Opposition. Parliamentary elections in 2002 gave the PSD enough seats to form a coalition government with the right-wing Portuguese People’s Party, and Barroso subsequently became Prime Minister of Portugal on 6 April 2002.

In March 2003, Barroso hosted U.S President George W. Bush, British Prime Minister Tony Blair and Spanish Prime Minister José María Aznar in the Portuguese island of Terceira, in the Azores. The four leaders finalised the controversial US-led 2003 invasion of Iraq. Under Barroso’s leadership, Portugal became part of the “coalition of the willing” for the invasion and occupation of Iraq, sending non-combat troops. On 30 January 2003, Barroso signed The letter of the eight supporting US. policy on Iraq.

Barroso did not finish his term as he had been nominated as President of the European Commission on 5 July 2004. Barroso arranged with Portuguese President Jorge Sampaio to nominate Pedro Santana Lopes as a substitute Prime Minister of Portugal. Santana Lopes led the PSD/PP coalition for a few months until early 2005, when new elections were called. When the Portuguese Socialist Party won the elections it produced an estimation that by the end of the year the budget deficit would reach 6.1%, which it used to criticise Barroso’s and Santana Lopes’s economic policies.

In 2004, the proposed European Constitution and now the Treaty of Lisbon included a provision that the choice of President must take into account the result of Parliamentary elections and the candidate supported by the victorious Europarty in particular. That provision was not in force in the nomination in 2004, but the centre-right European People’s Party (EPP), who won the elections, pressured for a candidate from its own ranks. In the end, José Manuel Barroso, the EPP candidate, was chosen by the European Council.

In 2005, Die Welt reported that Barroso had spent a week on the yacht of the Greek shipping billionaire Spiro Latsis. It emerged soon afterwards that this had occurred only a month before the Commission approved 10 million euros of Greek state aid for Latsis’s shipping company – though the state aid decision had been taken by the previous European Commission before Barroso took up his post. In response to this revelation, Nigel Farage MEP of the UK Independence Party persuaded around 75 MEPs from across the political spectrum to back a motion of no confidence in Barroso, so as to compel him to appear before the European Parliament to be questioned on the matter. The motion was tabled on 12 May 2005, and Barroso appeared before Parliament as required at a debate on 26 May 2005. The motion itself was heavily defeated.

In April 2008, amid sharp food price rises and mounting food vs fuel concerns, Barroso insisted that biofuel use was “not significant” in pushing up food prices. The following month, he announced a study that would look into the issue. The backdoor approval of the GE potato, by President Barroso, has met a wave of strong opposition from EU member-states. The governments of Greece, Austria, Luxembourg, Italy, Hungary and France have all publicly announced that they will not allow the GE potato to be grown in their countries.

On the same basis, the EPP again endorsed Barroso for a second term during the 2009 European election campaign and, after the EPP again won the elections, was able to secure his nomination by the European Council on 17 June 2009. On 3 September 2009, Barroso unveiled his manifesto for his second term. On 16 September 2009, Barroso was re-elected by the European Parliament for another five years. Since he completed his second term he became only the second Commission president to serve two terms, after Jacques Delors. That Commission’s term of office ran until 31 October 2014.

On 12 September 2012 Barroso has called for the EU to evolve into a “federation of nation-states”. Addressing the EU parliament in Strasbourg, Barroso said such a move was necessary to combat the continent’s economic crisis. He said he believed Greece would be able to stay in the eurozone if it stood by its commitments. Mr Barroso also set out plans for a single supervisory mechanism for all banks in the eurozone.

In December 2013 Barroso said that Europe was not the cause of the problems for Ireland; Ireland caused a problem for Europe. Following the bailout exit, in December 2013, the Irish government’s bid to get backdated funding for the banking sector was rejected as the head of the European Commission blamed the Irish banks, regulators and government for the difficulties in the country. Barroso said the problems in the Irish banks caused a “major destabilisation” in the euro, rather than structural problems with the currency itself, “I am saying this because it would be wrong to give the impression that Europe has created a problem for Ireland and now Europe has to help Ireland. In fact, it was the banking sector in Ireland—it was one of the biggest problems in the world in terms of banking stability what happened in Ireland.”

In July 2016, Barroso became the non-executive chairman of London-based Goldman Sachs International (GSI), the bank’s largest subsidiary. He is also an adviser to the bank. At the time of his appointments, this position was regarded as quite controversial, and later led Barroso’s successor Jean-Claude Juncker to launch an ethics investigation.

In 2020, Barroso was selected as chair of the board at GAVI, succeeding Ngozi Okonjo-Iweala.