UNICEF, in full called the United Nations Children's Fund, is an agency of the United Nations responsible for providing humanitarian and developmental aid to children worldwide. The agency is among the most widespread and recognizable social welfare organizations in the world, with a presence in 192 countries and territories. UNICEF's activities include providing immunizations and disease prevention, administering treatment for children and mothers with HIV, enhancing childhood and maternal nutrition, improving sanitation, promoting education, and providing emergency relief in response to disasters.UNICEF is the successor of the United Nations International Children's Emergency Fund, created on December 11, 1946, in New York, by the U.N. Relief Rehabilitation Administration to provide immediate relief to children and mothers affected by World War II. The same year, the U.N. General Assembly established UNICEF to further institutionalize post-war relief work. In 1950, its mandate was extended to address the long-term needs of children and women, particularly in developing countries. In 1953, the organization became a permanent part of the United Nations System, and its name was subsequently changed to its current form, though it retains the original acronym.UNICEF relies entirely on voluntary contributions from governments and private donors. Its total income as of 2020 was $ 7.2 billion; of which public-sector partners contributed $5.45 billion. It is governed by a 36-member executive board that establishes policies, approves programs, and oversees administrative and financial plans. The board is made up of government representatives elected by the United Nations Economic and Social Council, usually for three-year terms.

UNICEF's programs emphasize developing community-level services to promote the health and well-being of children. Most of its work is in the field, with a network that includes 150 country offices, headquarters and other facilities, and 34 "national committees" that carry out its mission through programs developed with host governments. Seven regional offices provide technical assistance to country offices as needed, while its Supply Division—based in Copenhagen and New York—helps provide over $3 billion in critical aid and services.

In 2018, UNICEF assisted in the birth of 27 million babies, administered pentavalent vaccines to an estimated 65.5 million children, provided education for 12 million children, treated four million children with severe acute malnutrition, and responded to 285 humanitarian emergencies in 90 countries. UNICEF has received recognition for its work, including the Nobel Peace Prize in 1965, the Indira Gandhi Prize in 1989 and the Princess of Asturias Award in 2006. During the 2020 COVID-19 pandemic, UNICEF, along with the World Health Organization and other agencies, published guidance about healthy parenting.