Buffalo Rock is said to have served the French as an early military, trading and missionary post. LaSalle and Tonty, after building Fort St. Louis on Starved Rock during the winter of 1882-1883 gathered almost 4,000 Indian warriors at the front of Buffalo Rock and formed a confederation against the Iroquois. Among the tribes in the confederation were the Miami who built their own fort on Buffalo Rock.
Through the many years that followed, Buffalo Rock was used by a religious sect as a place for holding camp meetings, and still later was used as a site for a tuberculosis sanatorium. The Crane Company of Chicago purchased Buffalo Rock in 1912 and for a period of about 16 years maintained a sanatorium for sick employees and a summer vacation ground for thousands of employees and their families. In 1927 the Crane Company moved their recreation park to a larger area and donated the land to the state to become a park. The deed to the property was turned over to the State of Illinois on November 15, 1928, with the provision that it would become a permanent state park and that the caretaker, Robert Barnett, who was then 72 years of age, be retained in that capacity during the remainder of his lifetime as a reward for his loyal services.