According to her obituary Katherine H. Mahan was born June 16, 1920 in Pontotoc, Mississippi to Terrell and David Hines. She graduated from South Side High School in 1938. She graduated from the New Orleans Baptist Seminary in 1948, and then received her BA in music from Oklahoma Baptist University in Shawnee, Oklahoma. She earned her master's degree in 1964 at Peabody University in Nashville and her PhD at Florida State University in 1967.

Dr. Mahan was a member of the National Federation of Music Clubs where she served as National Vice President, and all of the state-level positions. She was also a member of the National Federation of American Pen Women where she served as Vice President at the national level, and as President of both the state and local level. She was also active in the Orpheus Club of Music in Columbus, and a member of the choir of the First Baptist Church of Columbus. She was also the author of From Show Boats to Soft Shoes: 100 Years of Music in Columbus Georgia, 1828-1928 and the co-author of A History of Public Schools in Columbus, Muscogee County, Georgia: A Social History of Education in Muscogee County, 1828-1976.

She married Joseph Buford Mahan, Jr. in 1956 at Rose Hill Baptist Church in Columbus, Georgia. She taught briefly at Central High School in Phenix City, Alabama before beginning her career 1958 as a professor at the University of Georgia Extension Classes in Columbus. This later became Columbus College and still later Columbus State University, from which she retired in 1991. She died on November 2, 2001 and is buried in Parkhill Cemetery.