During the era of Mexican California, the area of modern-day Calero was originally part of Rancho San Vicente, granted in 1842 to José de los Reyes Berreyesa, of the prominent Berryessa family of California, by Governor Juan Bautista Alvarado.

[2] Rancho San Vicente remained in continuous operation as a grazing ranch until 2009, when the Peninsula Open Space Trust purchased the site and transformed it into the Rancho San Vicente Open Space Preserve (now integrated with Calero County Park).

[2] Calero is a neighborhood within the larger Almaden Valley district of San Jose, California.

It makes up the southwestern-most portion of South San Jose, located east of the Sierra Azul, north of the city of Morgan Hill, and west of Coyote Valley.

[5][6] Calero is largely a rural residential neighborhood,[1] but there are numerous working ranches in the area, such as the Californio Cattle Company.