Launching an appeal at a world summit in Jakarta, Annan said the 26 December catastrophe had likely killed more than 150,000 people and was the worst natural disaster the United Nations had ever had to respond to.
The UN chief said the figure of $977 million would provide for an immediate "focused set of programmes" that the UN and affected nations had agreed on.
"We must set the stage for efforts in the longer term, as we move from saving lives to recovery and reconstruction," he said.
He acknowledged that the pledges of billions of dollars from governments around the world had already far exceeded the money needed for the initial appeal.
Pledges to cash
But he urged all nations to quickly turn their pledges into cash and remain committed for the long term.
"Many of the pledges have come to us in cash and in kind. We need the rest of the pledges to be converted into cash quickly," he said.
"We also need more people and more materiel to get the aid to those who are most in need, often in remote areas."
"The past 11 days have been among the darkest in our lifetime. But they have also allowed us to see a new kind of light"
Annan said the carnage caused by the 9.0-magnitude earthquake off the coast of Indonesia's Aceh province and subsequent massive tsunami that swept across the Indian Ocean was "an unprecedented global catastrophe".
"For the United Nations, it is the largest natural disaster the organisation has had to respond to on behalf of the world community in the 60 years of our existence," he said.
The secretary-general commended governments and people around the world for their response.
He said the disaster had offered a "singular chance to prove our humanity" and the world had risen to the challenge and united.
"The past 11 days have been among the darkest in our lifetime. But they have also allowed us to see a new kind of light," he said.
"We have seen the world coming together. We have seen an opportunity to heal old wounds and long-running conflicts. We have seen everyone pull together - north, south, east and west."
Giving a breakdown of where some of the money was needed over the next six months, Annan said $229 million was for food and agriculture, $222 million for shelter and other urgent non-food items, $122 million for healthcare and $61 million for water and sanitation.
UN officials say the outcome of
the summit was encouraging
Speaking to Aljazeera from Jakarta, Kamal Marjan, UN assistance high commissioner for refugees affairs said the responses received at the summit were very encouraging.
"As the UN Secretary-General Kofi Annan said, the response and cooperation from the participating countries and development banks was very encouraging.
"We hope all aids pledged by the donor countries would be actually seen on the ground.
"The level of attendance was also highly appreciated especially when taking into consideration that invitations were sent just three days ago.
He also said a conference would be held on 11 January in which donor countries will officially announce their aids,amounting to $977 million.
"The amount will cover just 6-months emergency humanitarian aids," Marjan said.