Lightner was born on Aug. 15, 1921, in Raleigh, Lightner was the son of Calvin and Mamie Lightner, owners of a local funeral home. Lightner planned to someday work in the family business, and after high school attended North Carolina Central University. He was a quarterback of the football team and was a member of Omega Psi Phi Fraternity Inc. After graduation in 1941, he attended Echols College of Mortuary Science.
Like many African Americans, Lightner served his country in the U.S. Army during World War II. After his discharge, he returned to Raleigh to join his father in the family funeral home business.
Following the passage of the Voting Rights Act of 1965, he ran for Raleigh City Council and was first elected in 1967. He was subsequently elected mayor in 1973, winning support from both African Americans and whites to defeat a white businessman. He served only one term as mayor because, in 1977, Gov. Jim Hunt appointed him to fill an unexpired term in the NC Senate. Clarence Lightner died in 2002.