For the Portuguese island, see São Miguel Island.

San Miguel Island is the westernmost of California's Channel Islands, located across the Santa Barbara Channel in the Pacific Ocean, within Santa Barbara County, California. San Miguel is the sixth-largest of the eight Channel Islands at 9,325 acres (37.74 km² or 14.57 sq mi), including offshore islands and rocks. Prince Island, off the northeastern coast, measures in area. The island, at its farthest extent, is long and wide.