He attended the Camões Lyceum (now Camões Secondary School), where he graduated in 1965, winning the National Lyceums Award (Prémio Nacional dos Liceus) as the best student in the country. He studied physics and electrical engineering at Instituto Superior Técnico – University of Lisbon in Lisbon. He graduated in 1971 and started an academic career as an assistant professor teaching systems theory and telecommunications signals, before leaving academic life to start a political career.

In 1972, Guterres married child psychiatrist Luísa Amélia Guimarães e Melo, with whom he had two children, Pedro Guimarães e Melo Guterres (born 1977) and Mariana Guimarães e Melo de Oliveira Guterres (born 1985). His wife died of cancer at the Royal Free Hospital in London in 1998 at the age of 51.

Guterres’s political career began in 1974, when he became a member of the Socialist Party. Shortly thereafter, he quit academic life and became a full-time politician. In the period following the Carnation Revolution of 25 April 1974 that put an end to Caetano’s dictatorship, Guterres became involved in Socialist Party leadership and held the following offices:

Contrary to his party stance and following the removal of homosexuality from the list of mental illnesses by the World Health Organization in 1990, Guterres said, in 1995, that “he did not like homosexuality” and that it was “something that bothered him”.

Guterres was a member of the team that negotiated the terms of Portugal’s entry into the European Union in the late 1970s. He was a founding member of the Portuguese Refugee Council in 1991.

In 1992, after the Socialists’ third consecutive defeat in Parliamentary elections, Guterres became secretary-general of the Socialist Party and leader of the opposition during Aníbal Cavaco Silva’s government. At the time, he was the party’s third leader in six years. He was also selected as one of the 25 vice presidents of the Socialist International in September 1992.

With a style markedly different from that of his predecessor, and based on dialogue and discussion with all sections of society, Guterres was a popular prime minister in his first years in office. Portugal was enjoying an economic expansion that allowed the Socialists to reduce budget deficits while increasing welfare spending and creating new conditional cash transfer programs. His government also accelerated the program of privatizations that Cavaco Silva’s government had begun: 29 companies were privatized between 1996 and 1999, with proceeds from privatizations in 1996–97 greater than those of the previous six years, and the public sector’s share of GDP halved from 11% in 1994 to 5.5% five years later. Share ownership was also widened, with 800,000 people investing in Portugal Telecom upon its privatization in 1996 and 750,000 applying for shares in Electricidade de Portugal.

In 1998, Guterres presided over Expo 98 in Lisbon, commemorating the 500th anniversary of the voyage of Vasco da Gama. Also in 1998, two nationwide referenda were held. The first one was held in June and asked voters whether abortion rules should be liberalized. The Socialist Party split over the issue of liberalization, and Guterres led the pro-life side, which eventually won the referendum. A second referendum was held in November, this time over the regionalization of the mainland. Both Guterres and his party supported such an administrative reform, but the voters rejected it.

On foreign policy, Guterres campaigned for United Nations intervention in East Timor in 1999, after it was virtually destroyed by Indonesian-backed militias when it voted for independence. He also finalized the 12-year negotiations on the transfer of sovereignty over Macau, which had been a Portuguese colony, to Chinese control in 1999.

In the 1999 parliamentary election the Socialist Party and the opposition won exactly the same number of MPs (115). Guterres was reappointed to office and from January to July 2000 occupied the six-month rotating presidency of the European Council. His second term in government was not as successful, however. Internal party conflicts, an economic slowdown, and the Hintze Ribeiro Bridge disaster damaged his authority and popularity. Nevertheless, some long-lasting measures were taken during his second term: in October 2000, the Parliament approved the decriminalization of drug use (effective 1 July 2001) and in March 2001, same-sex civil unions were legalized.

Guterres was elected president of Socialist International in November 1999, overlapping with his second term as prime minister of Portugal until his resignation from the latter post in December 2001. He remained president of the Socialist International until June 2005.

In December 2001, following a disastrous defeat for the Socialist Party in local elections, Guterres resigned to “prevent the country from falling into a political swamp”. President Jorge Sampaio dissolved Parliament and called for elections. Eduardo Ferro Rodrigues, until then Minister for Social Security, assumed the Socialist Party leadership, but the general election was lost to the Social Democratic Party of José Manuel Durão Barroso, who later became President of the European Commission.

In 2001, Guterres married Catarina Marques de Almeida Vaz Pinto (b. 1960), a former Portuguese State Secretary for Culture and Culture Secretary for the City Council of Lisbon.

In 2005, following Guterres’s proposal, George Papandreou was elected vice president of the Socialist International; in 2006, Papandreou succeeded him as president of the Socialist International.

In May 2005, Guterres was elected High Commissioner for Refugees for a five-year term by the UN General Assembly, replacing Ruud Lubbers.

On 19–23 March 2006, Guterres visited Beijing, China, and expressed his objection to repatriation of North Korean refugees by the Chinese government.

The UN’s role in the Haiti cholera outbreak was widely discussed and criticized after the Ban Ki-moon administration denied the issue for several months. According to the Boston-based Institute for Justice & Democracy in Haiti as well as numerous conclusive scientific studies, the UN is the proximate cause for bringing cholera to Haiti. Peacekeepers sent to Haiti from Nepal in 2010 were carrying asymptomatic cholera and failed to treat their waste properly before dumping it into one of Haiti’s main water streams. During his UNSG informal dialogue, Jamaica, on behalf of the Caribbean Community, asked if the UN should assume liability for any deaths within local populations that result from the introduction of infectious disease by its peacekeepers. Jamaica also asked if Guterres believed compensation should be provided. Guterres responded by calling the situation a “particularly complex question”, saying it was difficult to preserve diplomatic immunity while also ensuring there is no impunity, but that he would “pay a lot of attention in trying to find the right equilibrium between these two aspects that are absolutely crucial”. In a UN General Assembly meeting in late October 2016, the representative from Haiti called the UN’s current and future response to the cholera epidemic “a litmus test of the system’s commitment to the promotion of human rights”. Though many had hoped Guterres’s term would mark a break with the inaction that characterized Ban’s response to the epidemic, Guterres has done little to signal a commitment to Haitian cholera victims. As of April 2017, five months into his term as secretary-general, only $10 million had been contributed to the $400 million fund to fight cholera and provide material assistance to victims the UN announced in 2016.

In what was widely considered a very effective PR move, Guterres appointed American actress Angelina Jolie as his special envoy to represent UNHCR and himself at the diplomatic level in 2012. Together they visited the Kilis Oncupinar Accommodation Facility in Turkey (2012); the Zaatari refugee camp in Jordan (2013); and the Maritime Squadron of the Armed Forces of Malta (2015). They also appeared jointly before the United Nations Security Council (2015).

In a February 2007 NPR interview devoted mainly to the plight of Iraqi refugees, Guterres said that this was one of the greatest refugee crises in the Middle East since 1948. Among poorly publicized refugee crises, he cited those in the Central African Republic and the Democratic Republic of the Congo. During his final years as High Commissioner, he worked chiefly to secure international aid for the refugees of the Syrian civil war, calling the refugee crisis an “existential” one for host countries (such as Lebanon and Jordan), and calling additional aid a “matter of survival” for the refugees. He was an outspoken advocate for a more coordinated and humane approach by European countries to the Mediterranean refugee crisis. In June 2013, he launched a US$5 billion aid effort, its biggest ever, to help up to 10.25 million Syrians that year.

In early 2015, the General Assembly voted to extend Guterres’s mandate by 6⁄2 months to 31 December, on recommendation of United Nations Secretary-General Ban Ki-moon. In light of the European migrant crisis, the UNHCR’s 98-member executive committee (EXCOM) later requested that Ban recommend extending Guterres’s term by another year, but Ban disregarded the request. Guterres left office on 31 December 2015, having served the second-longest term as High Commissioner in the organization’s history, after Prince Sadruddin Aga Khan.

In 2015, President Marcelo Rebelo de Sousa appointed Guterres to serve as a Member of the Council of State of Portugal; he resigned after being appointed as the UN’s 9th Secretary-General.

On 29 February 2016, Guterres submitted his nomination as Portugal’s candidate for the 2016 UN Secretary-General selection. This was the first time candidates for secretary-general had to present their platform in public hearings in the UN General Assembly, a process during which Guterres emerged as a much stronger candidate than had been initially expected, given that he fit the bill on neither the gender nor the geographic scores.

In 2016, Anders Kompass exposed the sexual assault of children by peacekeepers in the Central African Republic and, as a consequence, was dismissed by Ban’s administration before being rehabilitated in court. During the United Nations Secretary-General Candidate informal dialogues, Guterres indicated it was completely unacceptable that there be UN forces committing human rights violations such as rape and sexual violence. “All of us together—states and UN—must do our utmost to ensure that any kind of action of this type is severely punished,” he said. The United States raised the question of international tribunals to try peacekeepers for their crimes. Guterres responded by saying an independent jurisdiction would be excellent but that “the only way to get there is through a new compact with all key parties—true contributors, financial contributors—and to make sure that there is an adjustment in the relation between countries, the UN, and the support those that are contributing with troops receive, in order to be able to do it much better.” He also indicated that there is a gap between theoretical zero tolerance and the ineffective zero tolerance that actually exists on the ground and needs to be overcome.

Guterres became United Nations Secretary-General on 1 January 2017, following his formal election by the UN General Assembly on 13 October 2016.

On 5 October, the 15-member United Nations Security Council announced that it had agreed to nominate Guterres, after an informal secret ballot in which he gained 13 “encourage” votes and two “no opinion” votes. The Security Council officially nominated Guterres in a formal resolution on 6 October. A week later, he was formally elected by the United Nations General Assembly in its 71st session. Guterres took office on 1 January 2017.

On 1 January 2017, on his first day at the helm of the United Nations as secretary-general, Guterres pledged to make 2017 a year for peace. “Let us resolve to put peace first,” he said.

On 12 April 2017, Guterres appointed an 8-member Independent Panel to assess and enhance the effectiveness of UN-Habitat after Adoption of the New Urban Agenda. The panel’s recommendation to establish an independent coordinating mechanism, ‘UN-Urban’ met with criticism from urban experts and the African Urban Institute.

On 20 June 2017, “Secretary-General António Guterres warned the Trump administration … that if the United States disengages from many issues confronting the international community it will be replaced”.

After the violence during the 2017 Catalan independence referendum, Guterres trusted Spanish institutions to find a solution. He gave the same message when Catalonia declared independence on 27 October 2017 but said the solution should be made under the constitutional framework.

In March 2018, Guterres said the population of Syria’s Eastern Ghouta was living in “hell on earth”. In one district, 93% of buildings had been damaged or destroyed by December, according to UN satellite imagery analysis. A recent wave of bombings has caused further destruction.

In August 2018, Guterres called for an independent investigation into a Saudi Arabian-led coalition air strike in Yemen that killed 51 civilians, including 40 children.

In September 2018, during his address to the 73rd United Nations General Assembly, Guterres became the first secretary to say that advancing technology will disrupt labor markets like never before and to advocate stronger safety nets like Universal Basic Income.

In 2019, human rights groups criticized Guterres for being “silent” as China sent ethnic Uyghurs and other predominantly Muslim ethnic minorities to the Xinjiang re-education camps. Human Rights Watch chief Kenneth Roth said that Guterres “has been notably silent on one of the most important, … the most brazen human rights abuses, … because he is worried about upsetting the Chinese.”

In June 2019, Guterres stated that the “U.N. has the obligation to assume global leadership” in tackling climate change in the context of a visit to the pacific island of Tuvalu. He had previously supported other multilateral environmental initiatives, such as the Global Pact for the Environment that was put forward by France in September 2017.

In September 2019, Guterres condemned Israeli plans to annex the eastern portion of the occupied West Bank known as the Jordan Valley.

On 10 August 2020, responding to an explosion in Beirut, Guterres expressed his support for all people in need in Lebanon, especially women and girls who are most vulnerable in times of crisis. On 22 September, he appealed for global solidarity to overcome COVID-19, and again called for a global ceasefire by the end of 2020.

On 6 October 2020, Guterres expressed deep concern over the escalation of hostilities in the disputed region of Nagorno-Karabakh and called on Armenia and Azerbaijan to immediately halt fighting and progress towards a peaceful resolution.