Robertson county was formed in 1867. It is located in the Outer Bluegrass region of the state. The elevation in the county ranges from 550 to 1009 feet above sea level. In 2010 the county population was 2,282 in a land area of 99.91 square miles, an average of 22.8 people per square mile. It is the smallest county and the least populous county in the state.

The county seat is Mount Olivet.