Early life and career
Around 1817 Burnet attempted to establish a trading post at Natchitoches, Louisiana, to trade with Comanche Indians. After the venture failed, he moved into Texas, which was then a part of Mexico. After developing a bad lung disease, he recuperated while living among the Comanches. He was treated kindly for two years, and, in his return to civilization, asked that the Mexican prisoners be released with him and allowed to return home as well. The Comanches agreed to this proposal and the Mexican families were surprised that there was no ransom or other agreement to the release of these prisoners.

Early Texas years
Burnet received a land grant on 22 December 1826. Unfortunately, he was not able to raise the needed funds to bring the families to Texas, and he was forced to sell his share in the grant to finance their passage. He also sold his interest to the Galveston Bay and Texas Land Company. He did receive four leagues of land out of this deal. Unfortunately Mexico passed the Law of April 6, 1830 which forbid any more U.S. immigration to Texas. Burnet immediately built a sawmill on some adjacent land. His mill failed and he was also denied applications for more land by the Mexican government. Luckily, all the news wasn't bleak for Burnet. He married Hannah Este on 8 December 1830, in New Jersey. They had several children, but only one, William, lived to adulthood.

Texas empresario
Burnet was a delegate to the Convention of 1833. At the Convention of 1836, Burnet was chosen as interim president (serving from March 17 to October 22 1836) of the newly-formed Republic of Texas following the adoption of the Texas Declaration of Independence on 2 March. His vice-president was Lorenzo de Zavala. Burnet replaced Governor Henry Smith. After the smashing defeat of Santa Anna's forces at the Battle of San Jacinto, Burnet and Santa Anna signed the Treaties of Velasco on 14 May 1836.
On 5 September 1836, Texas voters elected a new president of the Republic of Texas—Burnet's political enemy Sam Houston. Burnet and Houston had never been on good terms, either in personal life nor in politics. On 22 October, Burnet suddenly resigned as acting president, yielding the office early to the newly elected President Houston, who had not been scheduled to take office until December. Houston was sworn into office at 4 p.m. that day. Burnet quietly retired to his farm near Lynchburg.
On 16 November 1838, Burnet reappeared in Texas politics when he was appointed Vice President of the Republic of Texas on the ticket of Mirabeau B. Lamar. And while serving as vice president, Burnet again took to the fields of combat and had an active part in the Cherokee Wars during Lamar's administration. By December 1840, Lamar became too ill to serve as president. Burnet again served as interim president, this time until the spring of 1841 in his stead.
At the end of Lamar's term, Burnet ran for the presidency against Houston. The two men openly attacked each other in the newspapers of the day. Houston signed his responses "Truth", and Burnet signed his "Publius". Burnet called Houston " a drunk, coward, a bad lawyer and a bad general". Houston accused Burnet of "treason, fraud, cowardice, drunkenness and hypocrisy". But when Houston called Burnet a hog thief, Burnet demanded a duel with Houston. An intermediary, Branch T. Archer, was sent to Houston, who replied "I am compelled to believe that the people are equally disgusted with both of us." When the votes were counted, Houston had received 75% of the tally, soundly defeating Burnet. A long-term political opponent of Houston, Burnet openly opposed Houston's plan to annex the Republic of Texas into the United States.

Later life

Burnet County, Texas, and its county seat, Burnet, Texas, were named in his honor in 1852.
The "Burnet Flag", the original Flag of Texas, is named after him.
Burnet Middle School in Union, New Jersey, is also named after him, as are many elementary and middle schools throughout Texas.
Burnet Road, a major north-south thoroughfare in Austin, Texas, is named for him.