Ambassador Maritza Chan is a Costa Rican career diplomat, academic, and activist. She was appointed Permanent Representative of Costa Rica to the United Nations on 15 August 2022 becoming the first Costa Rican woman to hold this position since Costa Rica signed the UN Charter in 1945. Before her appointment, Ambassador Maritza Chan served as Deputy Permanent Representative of Costa Rica to the United Nations from March 2020 to August 14, 2022.

Ambassador Maritza Chan has twenty-five years of professional experience at the highest political levels. She has represented Costa Rica before the United States and in multilateral organizations in both Washington, D.C. and New York.

In 2025, Ambassador Maritza Chan was elected Vice President of the Economic and Social Council (ECOSOC), with responsibility for the Humanitarian Affairs Segment. She also served as Vice President of the Bureau of the 69th session of the Commission on the Status of Women (CSW), where, in partnership with Cabo Verde, she led the consensus adoption of the Political Declaration marking the thirtieth anniversary of the Fourth World Conference on Women and the adoption of the Beijing Declaration and Platform for Action.

Ambassador Chan is an expert in international peace and security and a leading advocate for the establishment of governance frameworks for artificial intelligence and other emerging technologies. In this regard, she was appointed by the President of the 79th session of the UN General Assembly, Philemon Yang, as Co-Facilitator—alongside Ambassador Héctor Gómez, Permanent Representative of Spain to the United Nations—of the intergovernmental consultations on the establishment and functioning of the Independent International Scientific Panel on Artificial Intelligence and the Global Dialogue on Artificial Intelligence Governance, with a view to their adoption by the General Assembly in 2025.

In June 2024, the First Committee (Disarmament and International Security) elected Ambassador Maritza Chan by acclamation as Chair for the 79th session of the United Nations General Assembly. Ambassador Chan became the first female Permanent Representative to preside over the First Committee in the history of the United Nations. She is preceded only by Ambassador Mona Juul of Norway, who chaired the First Committee in 2006 in her capacity as Deputy Permanent Representative.

Ambassador Chan served as the President of the Fourth Review Conference of the United Nations Programme of Action to Prevent, Combat, and Eradicate the Illicit Trade in Small Arms and Light Weapons in All Its Aspects (UNPoA), held from June 18 to 28, 2024. The conference successfully adopted a consensus outcome document.

Additionally, Ambassador Maritza Chan served as Vice-Chair of the Open-Ended Working Group on Conventional Ammunition, which elaborated a set of political commitments to address existing gaps in through-life ammunition management (2022-2023). She was also Costa Rica's lead negotiator on the Arms Trade Treaty from 2010 to 2015.

She has been recognized twice by the United Nations Regional Centre for Peace, Disarmament and Development in Latin America and the Caribbean (UNLIREC) as one of the leading agents for change advocating for arms control, disarmament, and non-proliferation in 2014 and 2021. She has published multiple articles on her negotiating experience in disarmament, non-proliferation, and arms control. She has vast connections with international and regional organizations, as well as civil society and academia.

Ambassador Maritza Chan is part of the International Advisory Council (IAC) of the International Peace Institute (IPI). She is also a board member of the United Nations Democracy Fund (UNDEF). She served as Vice President of the 2023 Executive Board of the United Nations Development Programme, the United Nations Population Fund, and the United Nations Office for Project Services on behalf of the Latin American and Caribbean Group of States (GRULAC). She also served as President of the UNICEF Executive Board in 2022.

In 2018, Ambassador Chan returned to Washington D.C. as the Head of the Political Section of the Costa Rican Embassy (2018-2020) after acting as Coordinator of the Organization of the United States in San José, Costa Rica (2015-2017). Before this appointment, she served at the Permanent Mission of Costa Rica to the United Nations in New York (2010-2015). She also served at the Permanent Mission of Costa Rica to the Organization of American States in Washington D.C (2005-2009) and the Embassy of Costa Rica to the United States in Washington D.C (2002-2005). Ambassador Maritza Chan started her career as a Senior Speechwriter for the President of Costa Rica (1998-2002)