Librarian of Congress James H. Billington proposed the establishment of the WDL in a speech to the U.S. National Commission for UNESCO in June 2005. The basic idea was to create an Internet-based, easily-accessible collection of the world's cultural riches that would tell the stories and highlight the achievements of all countries and cultures, thereby promoting cross-cultural awareness and understanding. UNESCO welcomed the idea as a contribution toward fulfilling its strategic objectives, which include promoting knowledge societies, building capacity in developing countries, and promoting cultural diversity on the web. UNESCO Director-General Koichiro Matsuura designated UNESCO's Directorate for Communication and Information, then led by Dr. Abdul Waheed Khan, to work with the Library of Congress to develop the project.

In December 2006, UNESCO and the Library of Congress convened an Experts Meeting at UNESCO headquarters in Paris to discuss the project. Experts from all parts of the world identified a number of challenges that the project would need to overcome to be successful. They noted that little cultural content was being digitized in many countries and that developing countries in particular lacked the capacity to digitize and display their cultural treasures. Existing websites often had poorly developed search and display functions. Multilingual access was not well developed.

The Experts Meeting led to the establishment of working groups to develop guidelines for the project, and to a decision by the Library of Congress, UNESCO, and five partner institutions - the Bibliotheca Alexandrina, the National Library of Brazil, the National Library and Archives of Egypt, the National Library of Russia, and the Russian State Library - to contribute content to a WDL prototype to be presented at the UNESCO General Conference in 2007. Input into the design of the prototype was solicited through a consultative process that involved UNESCO, the International Federation of Library Associations and Institutions (IFLA), and individuals and institutions in more than forty countries. The successful unveiling of the prototype was followed by a decision by these institutions to develop a public, freely-accessible version of the WDL.

A team at the Library of Congress then developed the public, online version of the WDL, which was launched at UNESCO in April 2009. Twenty-six institutions in 19 countries contributed content to the launch version of the site. Launch partners included the national libraries of China, Egypt, Russia, France, the United States, and several other countries.

Following the launch, the WDL continued to add content to the site and to enlist new partners from all parts of the world.

In April 2010 institutions and organizations contributing to the WDL adopted the WDL Charter, which established a permanent governance structure that includes an annual partner meeting, an elected Executive Council, standing committees charged with providing advice to the Executive Council, and an institutional project manager. In 2020, the WDL Charter concluded. In order to preserve and maintain access to the collected materials, the Library is in the process of migrating the WDL collection to its main web site.