José María Estudillo (died April 8, 1830) was a Spanish-born Californio military officer and early settler of San Diego. He is the founder of the Estudillo family of California and served as Commandant of the Presidio of San Diego.

Commandant of the Presidio of San Diego from October 23, 1820, to September 1821 and again from 1827 to his death in 1830.

Estudillo married Gertrudis Horcasitas. In 1827 Estudillo's son, José Antonio Estudillo, built a large L-shaped adobe house for his father on land granted by Governor José María de Echeandía. The adobe was later enlarged and became U-shaped. The house is still standing, known as Casa de Estudillo, and is one of the oldest surviving buildings in California. It is located in Old Town San Diego State Historic Park, on the southeast side of the Old Town San Diego plaza, and is designated a National Historic Landmark in its own right.

José Antonio Estudillo was the grantee of Rancho Janal. Estudillo's other children were José Joaquin Estudillo, grantee of Rancho San Leandro, on the eastern shore of the San Francisco Bay; María Dolores Estudillo, who married Juan Bandini; and Magdalena Estudillo, the grantee who received Rancho Otay.

In December 1823 he was diarist with Brevet Captain José Romero when they were sent to find a route from Sonora (Mexico) to Alta California; on their expedition they first recorded the existence of Agua Caliente (hot water) at Palm Springs, California.^[1][2]