Fillmore is located in Southern California, northwest of Los Angeles. To the north of the town lie the mountains of Los Padres National Forest.
Under Mexican rule, the area became part of the Rancho Sespe Mexican land grant. A mini gold rush occurred along the river in 1842 (several years before Northern California's gold rush). In 1848 the region became part of the United States. The town was named after J.P. Fillmore, the railroad's superintendent. In 1914 the town was incorporated as a city.
Located off Highways 126 and 23, Fillmore is near the Los Padres National Forest and is east of Santa Paula and Ventura. There is also a Fillmore, New York.
Fillmore is part of the Ventura, California metro area.