Mary Guynn was born in Aiken. She received her undergraduate degree from the College of William and Mary and thereafter obtained her juris doctorate degree from Emory University. She is a partner in the law firm of Smith, Massey, Brodie, Guynn & Mayes, where she practices in the areas of residential and commercial real estate development and finance. Her professional memberships include the Georgia Bar Association and the South Carolina Bar Association. Her civic involvement includes the SPCA Albrecht Center for Animal Welfare, the Aiken Land Conservancy, Aiken Homebuilders Association, Greater Aiken Integrated Trails Foundation, Aiken County Habitat for Humanity, and Great Oak Aiken Therapeutic Riding Center. She enjoys showing hunter/jumper horses in her free time.