Fincher grew up in Birmingham and graduated in 1950 from Immaculata High School. She studied at Talladega College, West Virginia State College, the University of Alabama, Alabama State University and New York University.
After getting her master's degree at NYU she began her teaching career in Annapolis, Maryland. She returned to Birmingham to care for her mother Gertrude Sanders after an accident. She got a job teaching at Western Olin High School and transferred later to Hayes High School.
In the 1980s Fincher was the system-wide social studies coordinator. She assembled a curriculum for teaching African-American studies. She hosted a call-in television talk show on Birmingham cable called Pinnacles.
Fincher was active in community service, serving on the boards of the Birmingham Public Library, Birmingham Historical Society, Jefferson County Historical Commission, the Birmingham Civil Rights Institute. She co-founded the Institute on the Black Child program. For her lifetime of service she was honored as "Outstanding Woman in the Community" by the UAB Women's Center in 2001. She was part of Leadership Birmingham's class of 2003 and was given a service award by the National Conference for Community and Justice in 2006.
Fincher retired in 1999 and spent most of her time caring for her mother. She died at her Titusville home in 2009. She was survived by two daughters, Cherrye Parker and Cassandra Fells (both Birmingham teachers) and one granddaughter, Jasmine. Funeral services were held at Our Lady of Fatima Catholic Church and she is buried at Elmwood Cemetery.
- "Lillie Mae Harris Fincher" obituary (June 17, 2009) The Birmingham News
- Shelton, Melinda (June 23, 2009) "Library Mourns Loss of Board Member". Birmingham Public Library's Latest News, Reviews & Info
- Gray, Jeremy (June 28, 2009) "Birmingham veteran educator taught lessons in determination." The Birmingham News
- Lillie Fincher discusses To Kill a Mockingbird for Birmingham Public Library