The move has no direct impact on the six-nation efforts to strip Pyongyang of its ability to produce nuclear weapons.
However, it is a rare sign of reaching out to the international community by North Korea.
The Tac, which came into force in 1976, requires signatories to renounce the use or threat of force and calls for the peaceful settlement of conflicts.
Aside from the 10 Asean members, 11 other countries outside the regional bloc have signed the treaty.
The signing comes amid moves by North Korea to dismantle its nuclear program in exchange for economic and political incentives, including normalisation of ties with Japan and the United States.