Smith was born the youngest of four siblings in Queens, New York. She joined the Birmingham Police Department in 1985 and worked security details at several Birmngham Public Library branches in western Birmingham.
In January 2004 she was one of three officers who shared the Exchange Club "Officer of the Month" award for her part in counseling a suicidal woman to seek medical help.
Smith retired from the Birmingham force in 2005 and joined the Fairfield Police Department in August 2006. She was shot in the chest while detaining two men at her car on the morning of October 23, 2006. She was reporting to a report of a suspicious vehicle in the 5300 block of Avenue H in Fairfield's Vinesville neighborhood. Fellow officer Erick Burpo was wounded by gunfire after he pulled up seconds later. Smith was taken to UAB Hospital where she was later pronounced dead. Demetrius Jackson Jr, of Fairfield, was charged in the shootings and was convicted of capital murder on January 24, 2008. The verdict came a day after the jury reported a deadlock based on a shortage of evidence. Key prosecution witness Eliase Jackson was killed in Birmingham on October 26, 2007 in unrelated violence. Though prosecutors asked for the death penalty, the jury recommended a life sentence. Judge Theresa Petelos sentenced him to death, but the Alabama Court of Criminal Appeals determined that additional factors should have been considered and David Carpenter re-sentenced Jackson to life without parole.
Smith was survived by her mother, two sisters and a brother, as well as by her daughter RaSheka, a student at the University of Alabama. Her funeral was held at New Bethlehem Baptist Church in Bessemer, with interment at Elmwood Cemetery. In 2017 a section of I-59/20 between mile markers 115 and 116 was designated as the "Officer Mary Freeman Smith Memorial Highway".
- Norris, Toraine & Chanda Temple (October 24, 2006) "Slain officer remembered as special mother." The Birmingham News
- Gordon, Robert K. & Bill Plott (October 24, 2006) "Agents hunt officer's killers." The Birmingham News
- Gordon, Robert K. (October 25, 2006) "Suspect charged in officer's slaying". The Birmingham News
- Gordon, Robert K. (January 24, 2008) "Jurors recommend life without parole in officer's killing." The Birmingham News
- Robinson, Carol (October 30, 2017) "Highways dedicated to 7 Birmingham police officers killed in the line of duty." The Birmingham News
- Mary Smith at the Officer Down Memorial Page, Inc.