George Yeo, Singapore's foreign minister, told reporters: "We have agreed to create the human rights body."
"At the ministers' level we have a consensus," Yeo said. "Myanmar had a positive attitude towards all of this."
Setting up a human rights institution is an integral part of the charter that Asean is trying to complete before it is adopted at a summit of the region's presidents and prime ministers in November.
Earlier on Monday, Gloria Macapagal Arroyo, the Philippine president, called for unity in the region and a focus on Asean's goal of economic integration by 2015.
She said: "An Asean community is going to be anchored first and foremost on economic integration, with a focus on social justice and raising the standard of living in the region."
Analysts, though, warn that a human rights code will be difficult to achieve given the differing interpretations of the term within the Asean bloc.
According to one diplomat, Myanmar had originally opposed the idea, while Laos, Cambodia and Vietnam had asked for more time.
Until now, Asean, which celebrates its 40th anniversary next month, has operated without a constitution, relying instead on informal diplomacy and decision-making by consensus and has traditionally stuck to a policy of non-interference in each other's affairs.
Human rights groups have complained this policy of non-interference has allowed undemocratic governments to persist in the region.