Born in St. Johns, Michigan, his parents were Noble and Rose Clark Burnett. His father ran a dry goods store and as a youth, Burnett worked with his father in the store. He grew up watching his father designing ads to promote his business. During high school, he worked as a reporter for a local, rural newspaper in the summers.  After high school he went to study journalism at the University of Michigan and received his Bachelor’s degree in 1914. His first job was as a reporter at the Peoria Journal in Peoria, Illinois. 6] In his spare time he wrote and published various short stories between 1915 and 1921. After realizing the future growth possibilities in advertising, he moved to Detroit in 1917, and he got a job editing an in-house publication for Cadillac dealers called Cadillac Clearing House as a copywriter. He successfully went on to become an advertising director for the company.  In 1918, he married Naomi Geddes, whose father was a newspaper man.  He went on to have three children: Peter, Joseph and Phoebe.  During World War I he joined the Navy for six months.However, he never got to sea as he spent most of his time at Great Lakes building a breakwater, and hauling cement.  After his time in the Navy he returned to Cadillac for a short while. It was then when a few employees at Cadillac formed the LaFayette Motors Company. He moved to Indianapolis, Indiana as the advertising manager for the company.  With the company struggling, he found himself with an offer from Homer McKee. He left LaFayette and was hired to work for Homer Mckee Company as head of McKee’s creative operation. This was his first agency job. 8] After spending a decade working for McKee’s Company, and working through the stock market crash of 1929. He decided to move on if he was to amount to anything in the advertising business.  In 1930, he moved to Chicago and was hired by Erwin, Wasey ; Company and worked as the vice-president and the creative head of the company.  He worked for Erwin Wasey for five years and in 1935 he founded the Leo Burnett Company Inc.  On June 7, 1971, at the age of 79, he died of a heart attack at his family farm in Lake Zurich, Illinois.