Mahlangu was born in Pretoria on 10 July 1956, the second son of Martha Mahlangu. His father left in 1962 and as a result he was raised by his mother, a domestic worker. He attended Mamelodi High School up to Standard 8 (his tenth year of school), but his education was interrupted in 1976 by the riots of the Soweto uprising that resulted in school closures.