The University, now with the title Eötvös Loránd, was founded in 1635 by Cardinal Péter Pázmány (1570-1637) as a Catholic institution. Its original location was Nagyszombat (now Trnava in Slovakia), since large areas of the present Hungary were at that time the subject of continual dispute with the Ottoman Empire. The Eötvös University of Budapest also carries on the legacy of the University of Óbuda, founded in 1395.

The original faculties were Theology and Philosophy, where teaching began in the academic year 1635/36. Though the University had a strong Catholic character, the curriculum included mathematics and natural sciences, like physics and cartography, from the very beginning. 1667 saw the foundation of the Faculty of Law, and Medicine followed more than a century later, in 1769. Thus established with the classical European university structure of four faculties, state control was introduced in the same year by Queen Maria Theresa, who gave it the new name of the Royal Hungarian University (Magyar Királyi Tudományegyetem).

The Turks were expelled from Hungary at the turn of the 17th-18th centuries and Buda slowly regained its role as capital of the country. The University was moved to Buda in 1777. In the next decades its faculties were distributed among several buildings in Buda and Pest. The prosperity in the second half of the 19th century made possible the building of the campus in Museum Street, which is now the location of several departments of the Faculty of Science. In addition, the ever growing University acquired new buildings - now more than 100 - spread out all over Budapest.

The original language of teaching was Latin, and it was only about two hundred years ago that the Department of Hungarian Language was created. Hungarian became the main language in the course of the 19th century, and since 1861 it has been the official language of undergraduate teaching.

The structure of the university remained unaltered for almost two hundred years up to 1950 when significant changes were brought about by the communist takeover. The faculty of Theology was expelled from the University on ideological grounds, and the Faculty of Medicine became the separate Semmelweis Medical University. The Faculty of Philosophy and Art was divided into the Faculties of Science and Humanities. A more recent change was the incorporation of the Teacher Training College in 1983.

In 1950 the University was renamed after Baron Loránd Eötvös (1848-1919), a professor of physics of considerable significance (experimental evidence for the equivalence of gravitational and inertial mass) and an eminent statesman.

The Eötvös Memorial Day (Eötvös-nap) as well as the Pázmány Memorial Day (Pázmány-nap) held in the first half of May serve as the dates for distinguished lectures and official awards presented by the Dean of the Faculty and the Rector of the University.