He was an anti-apartheid activist and the last surviving co-defendant of the Rivonia Trial of 1963-64. The trial led to life prison sentences for eight activists, including Mlangeni, Nelson Mandela, Walter Sisulu and Denis Goldberg. He spent more than 25 years imprisoned on Robben Island. After his release, he served in Parliament after South Africa held its first open and democratic elections in 1994.
