Harry Thomas Burn was born to James LaFayette Burn (1866-1916) and Febb King Ensminger (1873-1945) in Niota, Tennessee on November 12, 1895. After graduating from high school, he worked for the Southern Railway Company (1913-1923) while simultaneously reading law and pursuing a political career. Burn was elected to the Tennessee House of Representatives in 1919 and served until 1923. In 1920, he cast the deciding vote ratifying the 19th (women's suffrage) Amendment to the U.S. Constitution. Because Tennessee was the 36th state to ratify, Burn's vote made the amendment an official part of the Constitution. When asked why he decided to vote for ratification even though it would likely end his political career, Burn replied that he believed that women had a right to vote, that the legislature had a moral and legal obligation to ratify, that he considered the vote an opportunity to free women from political slavery, that he believed that his actions would bring acclaim to his party in later years, and that I know that a mother's advice is always safest for a boy to follow, and my mother wanted me to vote for ratification. He also vehemently denied accusations that his vote had been determined by bribery.

Burn was admitted to the Tennessee Bar in 1923 and began practicing in McMinn County. He maintained his involvement in politics, running unsuccessfully for governor (1930), serving in the Tennessee State Senate (1949-1953), sitting on the state Planning Commission (1952-1972), and participating in four Tennessee Constitutional Conventions (1953, 1959, 1965, and 1971). Burn also worked for the Southern Railway Company (1942-1954), as President of the First National Bank of Rockwood (1950-1977), as Chairman and Trust Officer for the First National Bank and Trust Company in Rockwood (1965), and as the Senior Vice President of the Belted Galloway Society, Inc. (1967-1977). Burn was married twice, first to Mildred Rebecca Tarwater on October 25, 1933 and second to Ellen Folsom Cottrell (1908-1998) on February 14, 1937. He had one son with his second wife, Harry Thomas Jr. Harry T. Burn died on February 19, 1977 and is buried in New Cemetery in Niota, Tennessee.