Yesterday, announcing the results of the sixth straw poll, Vitaly Churkin, the Russian ambassador to the United Nations, said that Guterres had emerged as a clear favorite.
Portuguese officials have welcomed the choice as an honour for the country and a triumph for Portuguese diplomacy.
The UN Security Council on Wednesday unanimously chose Guterres, also former UN High Commissioner for Refugees (UNHCR) from 2005 to 2015, as its new head in January, Xinhua news agency reported.
Ban, presently in Italy, reacted from Rome on Thursday morning by calling Guterres' nomination as an "excellent choice", noting that he and Guterres had worked closely during the latter's "long and outstanding tenure" as the UN High Commissioner for Refugees.
The informal votes were used by the Security Council to thin the ranks of the 13 candidates who entered the race to become the new face of the UN.
Churkin cited his experience as prime minister and described him as "a person who talks to everybody, speaks his mind, a very outgoing, open person".
Speaking earlier, Mr Ban, 72, described Mr Guterres as a "superb choice" to succeed him in the role.
Although Mr Guterres's nomination was widely welcomed, there was disappointment among some campaigners who had hoped for the first female United Nations secretary general, or a candidate from Eastern Europe.
"Humility (is what I feel) about the huge challenges ahead of us, the awful complexity of the modern world".
"He showed deep compassion for the millions of people who were forced to leave their homes", Ban said, adding: "His past experience as Prime Minister of Portugal, his extensive knowledge of world affairs and his keen intelligence will serve him to lead the United Nations at a crucial period".
Antonio Guterres, High Commissioner for Refugees of UNHCR, attends a press conference November 4, 2015 in Berlin, Germany. "The two-hour presentation of each of the candidates in the General Assembly dialogues, and their collective Global Townhall debate, were important highlights and helped to include the global public in the debate about the future of the United Nations".
"But ultimately I think there was a general agreement among members of the Security Council and beyond that the most important thing is to have the best candidate available".
Guterres thanked the Security Council for nominating him to be the next Secretary-General.
"I would say that we have had a very fair process".
Human Rights Watch's United Nations director Louis Charbonneau said Antonio Guterres could "strike a radically new tone on human rights at a time of great challenge", but cautioned that he will be judged on his ability to stand up to the veto powers.