Mariposa Creek was named by the Spanish explorer Gabriel Moraga on September 27, 1806, when his expedition discovered a great cluster of butterflies ("mariposas" in Spanish and Portuguese): "We named this place Mariposas [butterflies] because these abounded, especially at night and during the morning. These butterflies became quite a nuisance. Their eagerness to escape the sun's rays was so pronounced that they pursued us closely everywhere and one of them got inside the ear of one of the privates, causing him great discomfort and us much trouble in extracting it." Each year on the first weekend in May, Mariposa residents mark the annual arrival of migrating monarch butterflies with a "Butterfly Days" festival and parade.
During the California Gold Rush, the Mariposa River was a rich gold-bearing creek and the site of several mining camps, including Logtown, Mariposa and Mariposita.