"This is, I believe, an historic opportunity." He recalled previous statements by Obama, who was elected on Tuesday, Nov 4 night and will take office on Jan 20, 2009 in which he spoke about the strong stake the US has in the UN.
This will be a "good opportunity not only for, the United States, but the United Nations as a whole to resolve all issues through dialogue," the Secretary-General said, expressing confidence that there will be greater cooperation between the organization and the US.
"If ever there were a time for the world to join together, it is now," he said, pointing to the global financial turmoil, climate change, reaching the anti-poverty Millennium Development Goals (MDGs) by their 2015 deadline and the twin food and energy crises.
Mr Ban said that he met Obama for the first and only time last year, shortly after taking office as Secretary-General, when they were seated next to each other on a flight between Washington and New York.
During the half-hour flight, Obama asked the Secretary-General many questions on the world body's goals and on issues such as North Korea, the Iranian nuclear issue and UN reform.
"He was very engaging and he knew a lot about the United Nations," Mr Ban said, adding that he was very encouraged by the encounter.
The Secretary-General also congratulated his "good friend," Vice President-elect Joseph Biden.
"With a glad heart, I welcome this new era of partnership for change," Mr Ban said, noting that he hopes to speak with Obama soon, both over the telephone and in person.