[4] It is named for David Gouverneur Burnet, the first (provisional) president of the Republic of Texas.

The name of the county is pronounced with the emphasis or accent on the first syllable, just as is the case with its namesake.

Later known tribes in the area include Tonkawa, Lipan Apache, and Comanche.

[5] During the 1820s-1830s, Stephen F. Austin and Green DeWitt conducted surveying and Indian-fighting explorations.

[5] In 1849, the United States established Fort Croghan,[6] and in 1848, the first settlers arrived in the county, Samuel Eli Holland, Logan Vandeveer, Peter Kerr, William Harrison Magill, Noah Smithwick, Captain Jesse B. Burnham, R. H. Hall, Adam Rankin "Stovepipe" Johnson, and Captain Christian Dorbandt.

[7] In 1851, 20 Mormon families under the leadership of Lyman Wight establish a colony at Hamilton Creek, later to be known as Morman Mill.

During 1882–1903, railroad tracks connected Burnet, Granite Mountain, Marble Falls, and Lampasas.

[5] During the Great Depression, county farmers suffered financially, but found work with government-sponsored public-works projects.