Nkosi was HIV-positive from birth, and was legally adopted by Gail Johnson, a Johannesburg Public Relations practitioner, when his own mother, debilitated by the disease, was no longer able to care for him.

[4] The young Nkosi Johnson first came to public attention in 1997, when a primary school in the Johannesburg suburb of Melville refused to accept him as a pupil because of his HIV-positive status.

The incident caused a furore at the highest political level – South Africa's Constitution forbids discrimination on the grounds of medical status – and the school later reversed its decision.

Nkosi was the keynote speaker at the 13th International AIDS Conference, where he encouraged people with HIV/AIDS to be open about the disease and to seek equal treatment.

[2] In November 2005, Gail represented Nkosi when he posthumously received the International Children's Peace Prize from the hands of Mikhail Gorbachev.