This official archival agency of UP established in 1974 and located in the Main Library, contains University records of permanent value and permanent papers of University administrators, faculty, and alumni. Foremost of these are the official records of the Board of Regents, Executive Committee, University Council, administrative officials of the University, individual records of Diliman colleges and units, official publications such as the UP Gazette, UP Newsletter, Philippine Collegian, reports of committees created by the University President and Board of Regents, memorabilia, plaques, trophies, pins, posters, photographs and theses and dissertations of the colleges.

On display at the Archives are contributions of the UP to the celebration of the Centennial of the Republic of the Philippines in 1989.

The Archives maintains computerized indexes to the Philippine Collegian, UP Gazette, and the Minutes of the Meetings of the Board of Regents for easy retrieval by officials, students and researchers.

A Conservation Laboratory was set up in the Archives in 2000.