The Universal Postal Union (UPU) - the UN specialized agency for postal matters - has formally acknowledged the Chagos Archipelago as an integral part of the territory of Mauritius. The decision was made by member countries who participated in the UPU's 27th Universal Postal Congress in Abidjan, Côte d'Ivoire, from the 9th to the 27th August, 2021. The decision was passed with 77 votes. There were six votes against the decision and 41 abstentions.

As a result of the decision, the UPU will no longer register, distribute or forward postage stamps issued by the "British Indian Ocean Territory". The Chagos Archipelago was previously recognized as part of the Overseas Territories of the United Kingdom.

In May 2019, following advice from the International Court of Justice, the UN General Assembly instructed the UN and its specialized agencies to recognize Mauritius' sovereignty over the Chagos Archipelago and refrain from recognizing or implementing any measure taken by or on behalf of, the "British Indian Ocean Territory".

As a UN specialized agency, the UPU is required to cooperate with and assist the UN and its principal and subsidiary organs and therefore
brought the matter to its primary governing body, the Congress, for decision.