Green was born into slavery on March 4, 1834 near Mount Sterling in Montgomery County, Kentucky. She was hired in 1890 by the R.T. Davis Milling Company in St. Joseph, Missouri, to represent "Aunt Jemima", an advertising character named after a song from a minstrel show. Davis Milling had recently acquired the formula to a ready-mixed, self-rising pancake flour from St. Joseph Gazette editor Chris L. Rutt and Charles Underwood and were looking to employ an African-American woman as a Mammy archetype to promote their new product. In 1893 Green was introduced as Aunt Jemima at the World's Columbian Exposition held in Chicago, where it was her job to operate a pancake-cooking display. Her amicable personality and talent as a cook helped establish a successful showing of the product, for which she received a medal and certificate from the Expo officials. After the Expo, Green was offered a lifetime contract to adopt the Aunt Jemima moniker and promote the pancake mix. This marked the beginning of a major promotional push by the company that included thousands of personal appearances and Aunt Jemima merchandising. Nancy Green maintained her job with Davis Milling (which was renamed Aunt Jemima Mills Company in 1914) until her death in 1923.