Beginning in the 1990s, UN peacekeeping has increasingly engaged in partnerships with regional organizations. The UN set up its first operation co-located with a regional peacekeeping force in Liberia in 1993. That force was deployed by the Economic Community of West African States. In 1994, the UN operation in Georgia began working with the peacekeeping force of the Commonwealth of Independent States (CIS). In the second half of the 1990s, operations such as UNMIBH in Bosnia and Herzegovina and UNMIK in Kosovo worked in tandem with NATO, the European Union and the Organization for Security and Cooperation in Europe (OSCE). In Afghanistan, the NATO-led International Security Assistance Force works closely with the UN political support mission.

More recently, other peacekeeping partners have stepped in to assist UN peacekeeping at critical moments to bridge gaps in deployment and strength and to further develop rapid response capabilities. In July 2003, in the Democratic Republic of the Congo, Operation Artemis, a French-led EU force, stabilized the situation in Bunia, Ituri province, where civilians were being targeted by warring factions. Authorized by the Security Council for 90 days, the force stabilized the situation, disarmed armed groups, saved thousands of civilians and bought time to allow the UN to assemble an expanded force to be deployed into Bunia.

In October 2003, in Liberia and more recently in Cote d'Ivoire, ECOWAS forces paved the way for the deployment of United Nations troops. Similar arrangements were made with the African Union peacekeeping mission in Burundi and the Multinational Interim Force in Haiti. In addition, regional brigades are being formed in Africa as part of the African Standby Force—an initiative of the African Union. In Darfur, the United Nations and the AU Mission in Sudan (AMIS) are working together through the deployment of a UN assistance cell in Addis Ababa; through their respective Special Representatives in Khartoum; and on the ground in Darfur.

The UN is cooperating with the AU in other parts of Africa, from MINURSO in Western Sahara to ONUB in Burundi, from UNOCI in Côte d'Ivoire to UNMEE in Ethiopia and Eritrea. UN support for AU peacekeeping became an even higher priority after the 2005 World Summit endorsed a 10-year African peacekeeping capacity building programme.

The United Nations has also continued its collaboration with the EU, including in particular in the DRC and in Kosovo, and sought to strengthen its cooperation with other regional organizations and arrangements, including NATO, OSCE, CIS and the Association of Southeast Asian Nations (ASEAN).