Hancock Park was developed in the 1920s, by the Hancock family, with profits earned from oil drilling in the former Rancho La Brea (much of which is now the Miracle Mile district). Hancock Park owes its name to developer-philanthropist G. Allan Hancock, who subdivided the property in the 1920s. Hancock, born and raised in a home at what is now the La Brea tar pits, inherited 4400 acres, which his father, Major Henry Hancock had acquired from the Rancho La Brea property owned by the family of Jose Jorge Rocha.

Some 71 oil wells were operating at capacity on the land from 1905 to 1910. Nine years later Hancock subdivided the property into residential lots. He leased 105 acres to the Wilshire Country Club with an option to buy. The Hancock Park development was started on Rossmore Avenue and moved west to Highland Avenue in 1921.

Architects such as Paul Williams, A. C. Chisholm and John Austin were hired to design homes for many of the city's pioneer families.