During a visit of Alfonso XIII to the institute in 1906, its director, Adolfo Cabrera Pinto, asked the King to re-establish the university. His petition was rewarded in 1913 by a decree that opened the first academic year of the Faculty of Philosophy and Letters and Law preparation. The classes were taught in the Institute under the direction of Cabrera Pinto.
This university sector was enlarged in 1917 when a course designed to prepare students to enter into the faculties of Medicine and Pharmacy was added. In 1921 La Laguna was once again able to consider itself a university city when the Law program was completed. However the actual University of La Laguna wasn't created until a Royal Decree issued on September 21st, 1927 made it the 7th Spanish university district. The Rector was the then dean-governor of the university sector, Jose Escobedo y González-Alberú. This royal decree definitively created the faculties of Law and Chemical Sciences and the Philosophy and Letters preparatory school, which was completed later.
The gradual enlargement of the faculties created the need to construct a new building for the University. In 1929 a public bid was published to design a new university building and residence hall on a plot of land belonging to the La Laguna municipal government in a place known as "El Cercado del Marqués". The design proposed by the architect Ceballos was chosen and in 1935 the construction project was authorised but it suffered heavy delays due to the Spanish Civil War and the new political regime that was established, among other reasons.
In 1942 Classic Language studies were incorporated, leading to the creation of the Faculty of Philosophy and Letters; five years later this was replaced by Romance Language studies. In 1960 the new university building was finally inaugurated in its entirety, in what is now the Central campus; at the time this campus held the faculties of Law and Sciences, the Central library, the Rectorate and the secretariats.
With these new facilities the University of La Laguna expanded. The departments of English Philology (1963), Biology (1967) and Mathematics (1969) were established along with the Faculty of Medicine (1968). The consequent growth of the institution included the incorporation of new studies, the division of the different disciplines and various other developments leading to the creation of new centres that today put the University of La Laguna on par with the best universities in Spain. The schools of Business Studies and Teacher Training were established in 1972 and one year later the Technical Architecture College was created.
The Faculty of Pharmacy was created in 1974 and the Faculty of Economics and Business Administration in 1975. The College of Nursing was established in 1977, one year before the Faculty of Sciences was divided and the faculties of Biology and Mathematics were created. In 1978 the College of Social Work was also created and in 1979 the Faculty of Fine Arts. In 1982 the old Faculty of Philosophy and Letters was divided into the faculties of Philology, Philosophy, Psychology and Education Sciences and Geography and History. 
In 1987 the old College of Nursing was renamed as the College of Nursing and Physiotherapy, in 1988 the Faculty of Information Sciences was established and in 1989 the faculties of Psychology and Physics. In the 1990s new centres were established that were more in line with the new Spanish university system, including Nautical and Ocean Studies and Computer Sciences (1990), Agricultural Sciences (1991) and Education (1995). Finally, in 1999 the Centre for Social and Political Sciences was established.
In addition, the ever-growing demand for advanced studies in the Canaries led the University of La Laguna to create the College of Las Palmas, offering studies in Medicine (1973) and undergraduate degrees in Law, Philology and Geography and History (1982). This school was governed by the University of La Laguna until 1989 when the University of Las Palmas de Gran Canarian was founded.