Jernigan grew up on a farm near Frisco City in Monroe County. He served in the U. S. Air Force for two years during World War II before moving to Birmingham and starting his career developing playground equipment.
Jernigan founded several companies during his career, including Plantation Patterns (now a division of Meadowcraft), United Chair Company (founded in 1969, now a division of Office Group America), Quick Marts (founded in 1973), and Winston Furniture (founded in 1976).
Jernigan has been a generous supporter of higher education, creating endowments at Birmingham-Southern College, Samford University, UAB and the University of Alabama. He has also funded scholarships and medical research.
Jernigan died of leukemia in January 2008. He was survived by his wife, Donna, four children and five grandchildren. He is buried at Elmwood Cemetery. He was inducted into the Birmingham Business Hall of Fame in 2021.