The University of Ceylon was established in 1942 by the Ceylon University Ordinance No.20 of 1942. With the establishment of the University, the two colleges – the Ceylon Medical College and the Ceylon University College were absorbed into the new institution. The University of Colombo Library inherited the Collection of books and periodicals collected by the University of Ceylon since 1942 onwards excluding the collection of Arts and Education, which was transferred to Peradeniya in 1952 and 1959 respectively.

Initially, the Library of the University of Colombo was housed in a rented building ‘Villa Venetia’ situated behind the College House premises. The Library of the University of Colombo was in temporary locations and shift here and there until 1999. The Science Library and the Law Library transferred from Peradeniya to Colombo in 1965 and have functioned at the College House with other small collections. In the faculty of Science, there are departmental libraries, i.e. Botany Department and Chemistry Department, were manned by the main Library Staff. The Faculty of Arts was established in 1964 and the library was housed at the Grand Stand Building.

In 1968, the Library at the College House and at the Grand Stand building was shifted to the National Pavilion Building which was constructed for the Industrial Exhibition. In 1986 it was moved  to the ground floor of  the Law Faculty Building. In mid-1997, there was a long felt need for a library of the University of Colombo. As its result, the existing library building was built up and came into functioning from November 1999. Part of the Science Library remained in the National Pavilion Building till 1982. In 1982 it was shifted to the New Chemistry Building and from there to the renovated Physics Building in 1992.

The University library started at College House with a collection of 2500 valuable books on History and Literature donated by Sir Ponnambalam Ramanathan in memory of his son A. Pathmanabha, and the collection received from two Colleges – the Ceylon Medical College and the University College. Since then every effort was taken to develop the Library Collection by purchased books and journals using the annual allocations, and gifts from well wishes. Organizations such as the Asia Foundation, The British Council, the Overseas Development Administration book presentation, The American Center, U.N.O. were named as a few. The Gulasekeram Collection was a worthy donation of Mathematics books added to the Science section of the Library.

With the establishment of 2nd Arts Faculty in 1964, a special book vote was granted to purchase books for the Library. The Asia Foundation donated multiple copies of textbooks needed for the Arts students and a Rental Library was set up in mid-1967. Books in the “Rental Library” were issued on a payment of 25cents per book for a period of one month. This service was very popular among the students during the period. In 1965, the Law Library was moved from Peradeniya to Colombo. The Law Collection was started with the donation of Mr. N. Nadarajah, (K.C.) and a comprehensive collection of Roman Dutch Law in Sri Lanka which was donated by Mr.Martinus Nijhoff. In 1975 the Departments of Education in the University of Peradeniya, in the University of Vidyodaya and University of Vidyalankara were brought to Colombo and Faculty of Education was established in the University of Colombo in 1976. The education collection was housed in the Department of Education and later transferred to the main library. In the main library, there are special collections, namely Sri Lanka Collection and the Rare book Collection. The Sri Lanka Collection was started in 1969 and the rare collection was developed by acquisitioned of the donation received Prof. M.B. Ariyapala, Mr. Kewal Motwani and Mr. Tissa Wijeratne. Material in these sections are strictly closed access and patronized mainly by the academic staff and local and foreign researchers. With the establishment of the Faculty of Graduate Studies (FGS) in 1987, FGS library was established in the College house and with the new Administration Building at Kumaratunge Munidasa Mawatha, the library was also moved to it. This was specifically for the use of Postgraduate students attached to the faculty in the special disciplines such as Management, Labour Studies, Women’s’ Studies and Information Systems.