Robert F. Barnett was an American politician who served as a member of the Illinois House of Representatives and the Illinois Senate.
Barnett was born in 1807 in Bourbon County, Kentucky. In 1832, he moved to DeWitt County, Illinois where he farmed land his father had purchased for him and served as a justice of the peace. Barnett was a Democrat known for his strong anti-slavery views.
Barnett served in the Illinois House of Representatives from 1840 to 1842 in the 12th Illinois General Assembly representing Macon and DeWitt counties; and then as a state senator from 1842 to 1844 in the 13th Illinois General Assembly representing McLean, Livingston, DeWitt, Piatt, and Macon counties. He returned as a state representative in the 17th Illinois General Assembly from 1850 to 1852 representing DeWitt and McLean counties.
In 1831, he married Margaret J. Mills; they had 10 children. He died in 1864 in Clinton, Illinois. His son, Nathan Barnett, ran for governor of Illinois on the Populist ticket in the 1892 Illinois gubernatorial election.