The University of California, Irvine (UCI or UC Irvine) is a public land-grant research university in Irvine, California, United States. One of the ten campuses of the University of California system, UCI offers 87 undergraduate degrees and 129 graduate and professional degrees, and roughly 30,000 undergraduates and 7,000 graduate students were enrolled at UCI as of Fall 2024. The university is classified among "R1: Doctoral Universities – Very high research activity" and had $609.6 million in research and development expenditures in 2023, ranking it 56th nationally. UCI became a member of the Association of American Universities in 1996.

The university administers the UC Irvine Medical Center, a large teaching hospital in Orange, and its affiliated health sciences system; the University of California, Irvine, Arboretum; and a portion of the University of California Natural Reserve System. UC Irvine set up the first Earth System Science Department in the United States. The university was rated as one of the "Public Ivies" in 1985 and 2001 surveys comparing publicly funded universities the authors claimed provide an education comparable to the Ivy League.

The UC Irvine Anteaters currently compete in the NCAA Division I as members of the Big West Conference. During the early years of the school's existence, the teams played at the NCAA Division II level. The Anteaters have won 28 national championships in nine different team sports, 64 Anteaters have won individual national championships, and 53 Anteaters have competed in the Olympics, winning a total of 33 Olympic medals.

As of May 2025, the school has had 5 Nobel Prize laureates, 7 Pulitzer Prize winners, 61 Sloan Research Fellowship recipients, 61 Guggenheim Fellows, and 1 Turing Award winner affiliated with the university as alumni, faculty or researchers. In addition, of the current faculty, 24 have been named to the National Academy of Sciences, 6 have been named to the National Academy of Medicine, 17 to the National Academy of Engineering, 41 to the American Academy of Arts and Sciences, and 20 to the National Academy of Inventors.