The Santa Barbara County area, including the Northern Channel Islands, was first settled by Native Americans at least 13,000 years ago. Evidence for a Paleoindian presence has been found in the form of a fluted Clovis-like point found in the 1980s along the western Santa Barbara Coast, as well as the remains of Arlington Springs Man found on Santa Rosa Island in the 1960s. For thousands of years, the area was home to the Chumash tribe of Native Americans, complex hunter-gatherers who lived along the coast and in interior valleys leaving rock art in many locations, including Painted Cave.

Europeans first contacted the Chumash in AD 1542, when three Spanish ships under the command of Juan Rodríguez Cabrillo explored the area. The Santa Barbara Channel received its name from Spanish explorer Sebastián Vizcaíno when he sailed along the California coast in 1602; his ships entered the channel on December 4, the day of the feast of Santa Barbara. Spanish ships associated with the Manila Galleon trade probably made emergency stops along the coast during the next 167 years, but no permanent settlements were established.

The first land expedition to explore California, led by Gaspar de Portolà explored the coastal area in 1769, on its way to Monterey Bay. The party traveled the same route on the return to San Diego in January 1770. That same year, a second expedition to Monterey again passed through the area. The DeAnza expeditions of 1774-76 followed Portola’s trail.

The Presidio of Santa Barbara was established in 1782 (4th of 5 in California), followed by Mission Santa Barbara in 1786 – both in what is now the city of Santa Barbara. The presidio and mission kept Vizcaino’s denomination, as did the later city and county – a common practice which has preserved the names of many of the 21 California Missions. Other missions in Santa Barbara County are located in Santa Ynez and Lompoc.

European contacts had devastating effects on the Chumash people, including a series of disease epidemics that drastically reduced the Chumash population. The Chumash survived, however, and thousands of Chumash descendants still live in the Santa Barbara area or surrounding counties. A tribal homeland was established in 1901, the Santa Ynez Reservation.

Following the Mexican secularization of the missions in the 1830s, the mission pasture lands were mostly broken up into large ranchos and granted mainly to prominent local citizens who already lived in the area. 604 of these land grants were later confirmed by the state of California, with 36 in Santa Barbara County.

Santa Barbara County was one of the 27 original counties of California, formed in 1850 at the time of statehood. The county’s territory was later divided to create Ventura County in 1873.