The seasoned actor and director discovered his true identity two years ago after 58 years of living a lie.
The 60-year-old revealed the startling details at the South African Film and Television Awards (Saftas) nominations party in Bryanston, Johannesburg, yesterday, where he received the Best Actor nod.
Mofokeng said he found out about his true identity when one of the senior Makhetha family members revealed who his father was.
Mofokeng is the surname of his stepfather who raised him.
"When I discovered that I am a Makhetha, I cried profusely. I have never cried like that before. I kept asking many questions trying to understand this.
"The man firstly apologised for not telling me that he was related to me, and who my father was. It was overwhelming. I am learning everyday who I am, and my new clan."
Mofokeng told Sowetan he was relieved to have found his real surname.
He shared that he was related to the famous Makhethas of Soweto who own a shopping centre in Jabavu and a B&B, among other businesses.
"I am excited to have discovered who I am. In fact I now feel a sense of relief now that I have found my identity, not that I was questioning it before. It is important for any African person to know his or her roots. I have lived for 58 years as a Mofokeng, so it is a big thing."
He said since he was a filmmaker he decided to turn the whole journey into a documentary.
"I traced my true roots to understand the history of the family. I started tracing it backwards, and how I came to be the person that I am."
Mofokeng said he was free to speak about his journey because the two families have performed the required traditional ceremonies.
"The Mofokengs have officially handed me over to the Makhethas. On the other side, Makhethas have accepted me. As we speak, we are currently busy with Home Affairs [Department], applying for a new identity."
Mofokeng attended Orlando West High School in Soweto in the 1970s.
He proceeded to Wits Drama School where he majored in acting. He furthered his education at Columbia University in the US where he obtained his Masters degree in theatre directing. He has worked as an associate artistic director at the Joburg Theatre, chief director of Mpumalanga department of sports and culture, and finally the artistic director of The State Theatre in Pretoria.