Santos was born on 10 August 1951 in Bogotá to Enrique Santos Castillo and his wife Clemencia Calderón Nieto, his brothers are: Enrique, Luis Fernando, and Felipe. The Santos family has been a well established and influential family since the mid-20th century; his great-great-grandaunt was María Antonia Santos Plata, a martyr of the Independence of Colombia, and his great-granduncle was Eduardo Santos Montejo, President of Colombia between 1938 and 1942, who acquired the national newspaper El Tiempo. From there, his family has been connected to the newspaper and influenced the political life of the country; Eduardo’s brother, Enrique, grandfather of Juan Manuel, and editor in chief of El Tiempo, was known as “Calibán” to his readers, and his three sons, Enrique (Juan Manuel’s father) and Hernando Santos Castillo, and Enrique Santos Molano were chief editor, director, and columnist respectively. Through his father’s brother, Hernando, and his mother’s sister, Elena, Juan Manuel is also first cousin on both sides to Francisco Santos Calderón, former Vice President of Colombia during the previous administration from 2002 to 2010.

Santos was born in Bogotá, Colombia. He attended Colegio San Carlos, a private secondary school in Bogotá, where he spent most of his school years until 1967, when he enlisted in the Colombian Navy and transferred to the Admiral Padilla Naval Cadet School in Cartagena, graduating from it in 1969, and continuing in the Navy until 1971, finishing with the rank of naval cadet NA-42z 139.

After leaving the Navy, Santos moved to the United States where he attended the University of Kansas. A member of Delta Upsilon fraternity, he graduated in 1973 with a Bachelor in Economics and Business Administration. On 31 October 2017, Santos received an honorary doctorate of human letters from KU.

After graduating from the University of Kansas, Santos served as Chief Executive of the National Federation of Coffee Growers of Colombia to the International Coffee Organization in London. During this time he also attended the London School of Economics, graduating with a Master of Science in Economic Development in 1975. He then attended the John F. Kennedy School of Government at Harvard University, graduating with a Master of Public Administration in 1981. He returned to Colombia to become Deputy Director of his family owned newspaper El Tiempo. Santos has been a member of the Washington-based think tank the Inter-American Dialogue since 1990, and he previously served as co-chair of the Board of Directors. He was president of the Freedom of Expression Commission for the Inter American Press Association.

A Fulbright visiting fellow at the Fletcher School of Law and Diplomacy at Tufts University in 1981, and a Nieman Fellow at Harvard University in 1988, Santos also holds an honorary Doctor of Laws degree.

He was Minister of Foreign Trade of Colombia during the administration of President César Gaviria Trujillo from 1991 to 1994, Minister of Finance and Public Credit of Colombia during the administration of President Andres Pastrana Arango from 2000 to 2002. In 1992 he was appointed President of the VIII United Nations Conference on Trade and Development.

In 1994 Juan Manuel Santos founded the Good Government Foundation, whose stated objective is helping and improving the governability and efficiency of the Colombian Government. This organization presented a proposal for a demilitarized zone and peace talks with the FARC guerrilla group. Juan Manuel Santos has been named as one of Time magazine’s 100 most influential people. Universidade NOVA de Lisboa is granting the Honoris Causa Doctorate title to Juan Manuel Santos.

Santos also founded the Social National Unity Party (Party of the U) to support the presidency of Álvaro Uribe. He was named Minister of Defence on 19 July 2006. During his tenure as Defence Minister, the administration dealt a series of blows against the FARC guerrilla group, including the rescue of Fernando Araújo Perdomo, the death of FARC Secretariat member Raúl Reyes (a controversial military raid on Ecuador’s border), and the non-violent rescue of former presidential candidate Ingrid Betancourt held captive since 2002, along with fourteen other hostages, including three Americans.

In 2008 the ‘false positives’ scandal was uncovered, referring to revelations concerning extrajudicial executions carried out by members of the military in order to artificially increase the number of guerrillas killed by the Army and claim rewards from the government. On 4 November 2008, Santos admitted that the military had carried out extrajudicial executions and he pledged to resolve the issue. Twenty-seven military officers, including three generals and eleven colonels, were sacked after an internal army investigation concluded that they were responsible for administrative failures and irregularities in reporting enemy casualties and operational results. The Commander of the Colombian National Army, General Mario Montoya, resigned. By May 2009, 67 soldiers had been found guilty and over 400 were arrested pending trial.

In June 2009, United Nations Special Rapporteur Philip Alston declared that extrajudicial executions had been carried out in a “more or less systematic manner” by numerous Colombian military personnel and found the number of trials for those implicated to be lacking, but stated that he had found no evidence of the executions being an official government policy and acknowledged a decrease in the number of reported cases.

Juan Manuel Santos announced his resignation from the Defence Ministry on 18 May 2009. Santos said that his resignation did not necessarily imply tossing his hat into the 2010 presidential race and that his participation in the electoral race depended on whether Uribe would pursue a third term, which he was willing to support. His resignation took effect on 23 May 2009. When the Constitutional Court ruled out the possibility of Uribe’s participation in the upcoming elections, Santos officially launched his campaign for the presidency of the Republic of Colombia.

In March 2010, Santos publicly stated these executions had stopped since October 2008 and that this had been confirmed by the CINEP, one of Colombia’s foremost human rights defence institutions. Semana, a well-respected weekly magazine, reported that a few days later the CINEP responded to Santos’s declarations by issuing a press release which stated that, while the number of reported cases had been significantly reduced after the Defence Ministry’s measures were announced, the period between November 2008 and December 2009 still saw 7 such executions and 2 arbitrary detentions.

On 20 June 2010, after two rounds of voting in the Presidential election, Juan Manuel Santos Calderón was officially elected as President of Colombia and was inaugurated on 7 August 2010 in the midst of a diplomatic crisis with Venezuela, which was quickly resolved.

On 15 June, Santos won 50.95% of the popular vote in the second round of the election. President Santos addressed supporters and volunteers gathered at the campaign’s headquarters in the Claustro de La Enseñanza after his reelection and said: “This is the end of 50 years of conflict in this country, and it is the beginning of a new Colombia”. Santos’s victory, which was much smaller than his landslide result in 2010, was credited with strategic endorsements from left-wing politicians such as Clara López who appeared on a T.V. endorsement for Santos despite having nearly polar opposite views on many issues. This helped Santos, who had been neck and neck with his Conservative challenger on polls up to the second election round. Many among the Left whose fortunes had declined since the start of the FARC insurgency hoped a peaceful negotiation with FARC, which required a Santos victory, would help rehabilitate the left among the Conservative-Liberal dominated political scene in Colombia.

Santos announced on 27 August 2012 that the Colombian government had engaged in exploratory talks with FARC in order to seek an end to the conflict. He also said that he would learn from the mistakes of previous leaders, who failed to secure a lasting ceasefire with FARC, though the military would still continue operations throughout Colombia while talks continued. According to an unnamed Colombian intelligence source, Santos offered FARC assurances that no one would be extradited to stand trial in another country. The move has been viewed as a cornerstone of Santos’ presidency. Former President Uribe has criticised Santos for seeking peace “at any costs” in contrast to his predecessor’s rejection of talks.

In October 2012, Santos received the Shalom Prize “for his commitment to seeking peace in his country and worldwide.” Upon accepting the award from the Latin American chapter of the World Jewish Congress, Santos stated that “Both the people here and the people in Israel have been seeking peace for decades,” adding that Colombia is in favour of a two-state solution to the Israeli-Palestinian conflict.

On 20 November 2013, Santos announced his intent to run for re-election in a presidential address, and formalised his intent by filing election papers with the National Civil Registry on 25 November. As the incumbent president he ran virtually unopposed in the Social Party of National Unity convention, receiving 772 votes of the 787 party delegates, and receiving the party’s nomination on 28 January 2014. Santos and his allies also lobbied for the support of other political parties, receiving the nomination from the Liberal and Radical Change parties, forming the National Unity Coalition.

During a Google hangout hosted by the Colombian newspaper El Tiempo on 20 May 2014, Santos voiced his support for same-sex marriage. “Marriage between homosexuals to me is perfectly acceptable and what’s more I am defending unions that exist between two people of the same sex with the rights and all of the same privileges that this union should receive,” said Santos.

In September 2016, Santos announced that an agreement had been made completely settling the dispute between the Colombian government and FARC on the basis of a truth and reconciliation-like process, in which a combination of complete admissions of guilt and community service on the part of perpetrators of misdeeds during the years of conflict would serve in place of retributive justice.

In May 2017, Donald Trump and Santos held a joint news conference at the White House, where Trump praised Colombia’s efforts to end a 52-year civil war that left more than 220,000 dead as a “great thing to watch.”

In September 2017, Santos defended Colombia’s record against U.S. President Donald Trump’s complaints about what he called unacceptable growth in coca cultivation and production. Trump added that he considered downgrading the country in a White House assessment, which would result in reduced development and security funding. One source of contention is the usage of glyphosate to eradicate coca crops, which Colombia had halted in favor of other methods due to health concerns.

On 14 March 2017 Santos acknowledged that his 2010 election campaign received illegal payments from Brazilian conglomerate Odebrecht.

In November 2017, an investigation conducted by the International Consortium of Investigative Journalism claimed Juan Manuel Santos was in control of two offshore companies in Barbados. Following this, Santos clarified that he left the managing board of one of these companies in prior to holding a ministerial office.

In July 2018, Santos called on Trump to urge Russian leader Vladimir Putin to stop supporting Venezuela’s authoritarian government. Santos has acknowledged that, in 2017, Trump raised the idea of a military invasion of Venezuela to drive out President Nicolas Maduro, which he and other Latin American leaders rejected at the time.