Irvine was inhabited by the Gabrielino indigenous group about 2,000 years ago. Gaspar de Portolà, a Spanish explorer, came to the area in 1769. This brought on the establishment of forts, missions and herds of cattle. The King of Spain parceled out land for missions and private use.
After Mexico's independence from Spain in 1821, the Mexican government secularized the missions and assumed control of the lands. It began distributing the land to Mexican citizens who applied for grants. Three large Spanish/Mexican grants made up the land that later became the Irvine Ranch: Rancho Santiago de Santa Ana, Rancho San Joaquin and Rancho Lomas de Santiago.
In 1864, Jose Andres Sepulveda, owner of Rancho San Joaquin sold 50,000 acres (200 km2) to Benjamin and Thomas Flint, Llewellyn Bixby and James Irvine for $18,000 to resolve debts due to the Great Drought. In 1866, Irvine, Flint and Bixby acquired 47,000-acre (190 km2) Rancho Lomas de Santiago for $7,000. After the Mexican-American war the land of Rancho Santiago de Santa Ana fell prey to tangled titles. In 1868, the ranch was divided among four claimants as part of a lawsuit: Flint, Bixby and Irvine. The ranches were devoted to sheep grazing. However, in 1870, tenant farming was permitted.
In 1878, James Irvine acquired his partners' interests for $150,000. His 110,000 acres (450 km2) stretched 23 miles (37 km) from the Pacific Ocean to the Santa Ana River. James Irvine died in 1886. The ranch was inherited by his son, James Irvine, Jr. who incorporated it into The Irvine Company. James, Jr. shifted the ranch operations to field crops, olive and citrus crops.
In 1888, the Santa Fe Railroad extended its line to Fallbrook Junction (north of San Diego) and named a station along the way after James Irvine. The town that formed around this station was named Myford, after Irvine's son, because a post office in Calaveras County already bore the family name. The town was renamed Irvine in 1914.The developing urban core in the City of Irvine.
By 1918, 60,000 acres (240 km2) of lima beans were grown on the Irvine Ranch. Two Marine Corps facilities, MCAS El Toro and MCAS Tustin, were built during World War II on ranch land sold to the government.
James Irvine, Jr. died in 1947 at the age of 80. His son, Myford, assumed the presidency of The Irvine Company. He began opening small sections of the Irvine Ranch to urban development. Myford Irvine died in 1959. The same year, the University of California asked The Irvine Company for 1,000 acres (4 km2) for a new university campus. The Irvine Company sold the requested land for $1 and later the State purchased an additional 500 acres (2 km2).
William Pereira, the University's consulting architect, and The Irvine Company planners drew up master plans for a city of 50,000 people surrounding the new university. The plan called for industrial, residential and recreational areas, commercial centers and greenbelts. The new community was to be named Irvine; the old agricultural town of Irvine, where the railroad station and post office were located, was renamed East Irvine. The villages of Turtle Rock, University Park, Culverdale, the Ranch and Walnut were completed by 1970.
On December 28, 1971, the residents of these communities voted to incorporate a substantially larger city than the one envisioned by the Pereira plan. By January 1999, Irvine had a population of 134,000 and a total area of 43 square miles (111 km2).