The draft resolution, hammered out in negotiations over the weekend, will be presented for adoption to health ministers at the WHO's three-day special assembly that opens on November 29, they said.
The diplomatic breakthrough came amid growing international concern over the new coronavirus variant Omicron, first detected in South Africa this month, which has spread further around the world.
A global agreement to strengthen pandemic prevention and responses, expected to be ready in May 2024, would cover issues such as sharing of data and genome sequences of emerging viruses, and of any potential vaccines and drugs derived from research.
"This decision, to establish a negotiating body on a future pandemic agreement, may only be the end of the beginning, but the flexibility shown and the breadth of support is a good portent for the vital efforts to come," Simon Manley, Britain's ambassador to the United Nations in Geneva, said in a statement.
Britain, along with the EU and some 70 other countries, had pushed for a legally binding treaty. The United States backed by states including Brazil and India was reluctant to commit to a binding treaty, diplomats said last week.
"There is agreement on a text which for us is very satisfying," a European diplomat said. "It also gives the Americans a way out, who are clearly joined up."
"It is a good outcome... There was enormous goodwill to get common language," said another diplomat.
The draft resolution was posted on the WHO website.
Photo file Caption: World Health Organisation headquarters in Geneva