List of parties to the Treaty on the Prohibition of Nuclear Weapons

The list of parties to the Treaty on the Prohibition of Nuclear Weapons encompasses the states which have signed and ratified or acceded to the Treaty on the Prohibition of Nuclear Weapons, a multilateral treaty outlawing nuclear weapons.

On 20 September 2017, the treaty was opened for signature.^[1] Following Article 15 of the treaty, it entered into force on 22 January 2021 after it had been ratified by 50 states.^[1][2] States have the option of acceding to the treaty without signing.

A total of 197 states may become parties to the Treaty on the Prohibition of Nuclear Weapons, including all 193 member states of the United Nations, the Holy See, the State of Palestine, the Cook Islands, and Niue. As of January 2024, 70 states have ratified or acceded to the treaty, most recently São Tomé and Príncipe.^[1]