Guterres has his work cut out for him. He is inheriting some of the most complicated challenges to peace and security that the world faces, including the war in Syria and the migrant crisis.
Former Portuguese Prime Minister Antonio Guterres is all set to take on what is arguably one of the toughest diplomatic jobs in the world. His appointment as the next secretary general of the United Nations got the unanimous backing of a deeply divided Security Council, underscoring Guterres' strong negotiation and persuasion credentials.
That Guterres is the first former head of government chosen to helm the world body is a clear signal that member countries wanted a secretary general with significant clout and strong leadership skills to steer the United Nations through one of the toughest times in its 71-year history.
"In the end, there was just a candidate whose experience, vision, and versatility across a range of areas proved compelling. And it was remarkably uncontentious, uncontroversial," said Samantha Power, the US ambassador to the UN.
"If we have these transnational threats and we don't have somebody at the helm of the United Nations that can mobilize coalitions, that can make the tools of this institution – creaky though they are, flawed though they are – work better for people, that's going to be more pain and more suffering and more dysfunction than we can afford," she said.
Guterres emerged the winner from a pool of candidates that included former heads of state, top diplomats and chiefs of UN agencies in a process that was more transparent than usual and involved open hearings. He beat out top contenders such as former New Zealand Prime Minister Helen Clark, who was vying to be the first woman to lead the world body, and former president of Slovenia Danilo Turk.
As the UN High Commissioner for Refugees, Guterres was known for taking on powerful countries, including the United States, often criticizing them for not doing enough to resettle Syrian refugees. This is in contrast to the man he is going to succeed – Ban Ki-moon, a soft-spoken diplomat, who, to his critics, is too reluctant to take on the major powers.
"As secretary general, he would be bullied and pressured and occasionally even blackmailed. It's an extremely difficult job. We hope Mr. Guterres performs admirably well when he is put to the test but it's not going to be easy," UN director of Human Rights Watch, Louis Charbonneau told DW.
Guterres served as the prime minister of Portugal from 1995 to 2002. He is credited for spearheading Portugal's entry into the European single market by implementing a series of financial reforms.
During his stint as prime minister, Guterres, eloquent in English, French and Spanish, emerged as one of the most admirable leaders in Europe. The then UK prime minister Tony Blair even viewed him as a suitable person to run the European Commission.
"I am certain that he can do justice to the big responsibility by giving a face and a voice to the United Nations as a result of his experience and his personality," said German Foreign Minister Frank-Walter Steinmeier in a statement on Thursday.
The veteran politician has his work cut out for him. He is inheriting some of the most complicated challenges to peace and security including the war in Syria, the displacement of more than 65 million people, terrorism perpetrated by the so-called Islamic State, North Korea's provocative nuclear program and climate change.
The 67-year-old Guterres' first challenge would be to bring stability in Syria – a task that has only become more difficult with the two veto powers - Russia and United States – bitterly at odds over the protracted conflict and no longer talking about a ceasefire.
Guterres will be confronted with a host of challenges, including the Syrian civil war and an the ongoing migration crisis
He will also need to bring his decade-long experience as the chief of UN refugee agency in good use in tackling the migrant crisis – the worst since the Second World War. He would hope that the world powers, who ignored his call for more funds and resources to tackle the crisis during his stint in the UN refugee agency, will finally listen to him when he takes over the top job.
He has the daunting task of restoring the reputation of the UN peacekeeping forces, which have repeatedly faced accusations of sexual abuse and other human rights violations.
"The secretary general is going to be judged by his ability to stand up to the very powers that have just selected him as the next secretary general," said Charbonneau.
"There are going to be times when the secretary general would have to push the member states to do things that they don't want to do, to do things that he sees as right. This is going to be difficult and if he does not stand up to the big powers then he may find himself being judged harshly."