Privacy International (PI) is a UK-based registered charity that defends and promotes the right to privacy across the world. First formed in 1990, registered as a non-profit company in 2002 and as a charity in 2012, PI is based in London. Its current executive director, since 2012, is Dr Gus Hosein.

During 1990, in response to increasing awareness about the globalization of surveillance, more than a hundred privacy experts and human rights organizations from forty countries took steps to form an international organization for the protection of privacy.

Members of the new body, including computer professionals, academics, lawyers, journalists, jurists, and activists, had a common interest in promoting an international understanding of the importance of privacy and data protection. Meetings of the group, which took the name Privacy International (PI), were held throughout that year in North America, Europe, Asia, and the South Pacific, and members agreed to work toward the establishment of new forms of privacy advocacy at the international level. The initiative was convened and personally funded by British privacy activist Simon Davies who served as director of the organization until June 2012.

At the time, privacy advocacy within the non-government sector was fragmented and regionalized, while at the regulatory level there was little communication between privacy officials outside the European Union. Awareness of privacy issues at the international level was generated primarily through academic publications and international news reports but privacy campaigning at an international level until that time had not been feasible.

While there had for some years existed an annual international meeting of privacy regulators, the formation of Privacy International was the first successful attempt to establish a global focus on this emerging area of human rights. PI evolved as an independent, non-government network with the primary role of advocacy and support, but largely failed in its first decade to become a major international player. Most of its early campaigns were focused on Southeast Asia.

From 2011, Privacy International began to formalize and condense its operations. It is now a UK-registered charity (number 1147471) with twenty full-time members of staff and an office in Central London. As part of restructuring, an informal advisory board was replaced in 2012 by a managing 9 member board of trustees, including investigative journalist Heather Brooke and technologist Jerry Fishenden. The restructuring also established three major program areas: contesting surveillance, challenging data exploitation, and building a global privacy movement.

Privacy International's Articles of Association state that the charity's objective is to promote the human right of privacy throughout the world, as set out in the Universal Declaration of Human Rights and subsequent United Nations conventions and declarations; specifically:

Privacy International has been funded and supported by a variety of foundations, academic establishments, and non-government organizations, including the Adessium Foundation, the Open Society Foundations, the International Research Development Centre, the European Parliament, the European Commission, the Joseph Rowntree Reform Trust, the Esmée Fairbairn Foundation, the University of Toronto's Canada Centre for Global Security Studies in the Munk School of Global Affairs, the American Civil Liberties Union, the Electronic Privacy Information Center, The Fund for Constitutional Government, the Stern Foundation, the Privacy Foundation, the German Marshall Fund, the University of New South Wales, the German Permanent Mission to the UN, the Oak Foundation, the Renewable Freedom Foundation, the Omidyar Network, the Roughley Charitable Trust, the Swedish International Development Agency, and the Street Foundation. It also receives a small amount of finance via contributions.