Mofokeng was a member of the Soweto Student Representative Council (SSRC) at the time of the Soweto uprising. After the uprising she was one of the hundreds detained. While in detention she was beaten and tortured in an attempt to gain information, but she kept silent. After three months she was released, to find that she had been expelled from her school, but her father arranged that she could still attend classes. In 1979 she was again arrested, this time for helping organise a funeral for Comrade Matsobane who had died on Robben Island.
In 1984 Mofokeng decided to leave Soweto for Sebokeng where she helped in the forming of the Vaal Organisation of Women, and then became secretary of the organisation. Through the organisation she set about addressing the problems facing the people, and organised a rent boycott and a stay-away in connection with the resignation of the local councils. The police arrived at her door demanding she stop the stay-away, but she refused.
At the march that took place a few days later, violence broke out when a councillor who was called on to join the march started shooting on the marchers. Five people were killed, including the councillor. As a result of this, Mofokeng was once again arrested, and this time taken to John Voster Square. Here she was tortured and underfed until she fell unconscious. She was then taken to hospital and brought back to her cell. On a second trip to the hospital she managed to escape and fled into exile. Once in exile Mofokeng was sent to Russia for special medical care, where it was discovered that she had been given poison that was slowly eating her intestines. She was operated on and that damage was repaired.