New Zealand ratified the Cluster Munitions Disarmament Convention at the United Nations in New York today.
Legislation implementing the move was passed by Parliament earlier this month.
Cluster bombs are canisters dropped from aircraft that open above ground and release large numbers of small bombs.
Many do not explode on impact and remain lethal for years, killing or maiming civilians.
Disarmament and Arms Control Minister Georgina te Heuheu said ratification meant New Zealand could take part in the first meeting of signatories in Laos next year.
New Zealand played a key role negotiating the convention, Mrs te Heuheu said.
"New Zealand plans to be an active advocate for this convention.
"The more states that commit to it the stronger the norm against cluster munitions will become."
The convention bans the use, development, production and stockpiling of cluster munitions.
New Zealand's permanent representative to the UN Jim McLay attended a brief ceremony this morning where the ratification was documented.
NZPA