His initial political involvement against the Apartheid regime started in 1944 during the Alexandra bus boycott, a non-violent protest campaign.

In the same year he was arrested for participating in the nationwide South African Potato Boycott, following The Farm Labour Scandal, a journalistic investigation by Ruth First and Joe Gqabi, which uncovered that Africans arrested for infringement of the pass laws were coerced into enforced labour on potato farms.

In 1958 Thomas Nkobi became the National Organizer of the ANC and was charged with the task of implementing the M-Plan, an action plan, named after Nelson Mandela, to decentralise the ANCs organizational branches and communication channels to avoid public meetings and announcements and increase effectiveness of their political and social campaign.

In 1963 Thomas Nkobi fled South Africa for exile in Dar es Salaam / Tanzania and later Lusaka / Zambia, where he became actively involved in mobilising international public opinion against the Apartheid regime.

In 2004, Thomas Nkobi posthumously received the Order of Luthuli in Gold for his "exceptional and selfless contribution to the struggle for a non-racial, non-sexist, free and democratic South Africa".