Dr Surin Pitsuwan ends his five-year term as secretary general in December, to be replaced by Vietnamese Deputy Foreign Minister Le Luong Minh.
He's told Australia Network's Asia Pacific Focus ASEAN's role after Cyclone Nargis in 2008, in which at least 138,000 people died, was instrumental in bringing the formerly reclusive Burma into closer contact with the West.
"We brought the world in, we brought the UN in," he said.
"Myanmar then was a different category, [a] different kind of country, [and] one of the most gratifying experiences has to be the opening up of Myanmar.
"Which I think ASEAN has contributed to by engaging them, bringing the world in, and raising the level of comfort of the leadership of Myanmar, the people of Myanmar, that the world is, after all, not very, very hostile."
Dr Pitsuwan says the emergence of ASEAN as a more significant regional player, as evidenced by the presence of the US and China, during last week's talks in Cambodia, has brought its own challenges.
"I think what we realise is we have to be a neutral broker of all these power plays, if I may use that term, between and among external powers around us," he said.
"We can't do it alone - to achieve our own objective, our own vision of one community here among us 10, we need to involve a lot of them."
The Cambodia talks were overshadowed by ongoing disputes between several regional countries and China over the sovereignty of several disputed islands in the South China Sea.
Dr Pitsuwan says the issue will continue to present challenges, but he believes the ASEAN forum is in a position to discuss them in a civil manner.
"We are still growing together," he said.
"We are still trying to integrate not only economically but in norms, in perceptions, in vision, and in the way in which we handle our differences.
"The way in which the issue was brought up was very civil, was very courteous to each other - we have our interests in the stability and security of this particular body of waters."