The Channel of Santa Barbara was discovered as early as 1542, but was named by Spanish explorer Sebastian Viscaino on December 4, 1602. As this day is considered sacred to Saint Barbara, the patroness of artillerymen and miners, Viscaino named it in honor of her.

In 1782, Father Junipero Serra met with California Governor Filipe de Neve about constructing a presidio and mission in the area to convert the local Chumash natives. Governor de Neve had long been an opponent of the Franciscan missionaries, whom he felt were growing too powerful in California. He went along with the building of El Presidio, but balked at the construction of the mission. Father Serra tried to change the governor's mind, but de Neve could not be swayed. Defeated, Father Serra returned to his home mission in Caramel. When Pedro Fages replaced de Neve as governor four years later, he granted the Franciscans permission to build the mission. Sadly, Father Serra never lived to see his dream realized, as he died just one month later. Mission Santa Barbara was founded on December 4, 1786 by Serra's successor, Father Fermin Francisco de Lasuen.