Jaume I University (Spanish: Universidad Jaime I, Valencian: Universitat Jaume I, UJI; IPA: [univeɾsiˈtad ˈdʒawme pɾiˈmeɾ]) is a university in the city of Castelló de la Plana, Valencian Community, Spain.

It is named after James I of Aragon (Jaume I in Valencian), who founded the Kingdom of Valencia.

The university is open to new schemes that help enhance the quality of the teaching and the research carried out here.

Some of the more noteworthy initiatives related to teaching include the UNESCO Chair on the Philosophy of Peace, the Jean Monnet Chair of Law and European Economics Module, as well as the EURINSA and EURUJI programmes for the training of engineers in Europe.

The area with the strongest research performance is chemistry, in particular the Institute of Advanced Materials, with scientists such as Juan Bisquert (Professor of Applied Physics) and Iván Mora-Seró among the world's most cited researchers in the annual ranking published by Clarivate Analytics.