Martins was a member of the Black Consciousness Movement beginning in the 1970s. He was utilized for his artistic background after having studied at Bill Ainslie's studio and at the Federated Union of Black Artists with the likes of Johnny Rieberio, Fikile Magadlela and Thamsanqa Mnyele. As a graphic artist, he produced protest T-shirts and made posters for the movement, later producing the famous poster distributed at Steve Biko's funeral. In the late 1970s, he traveled to Botswana and Lesotho to meet with activists-in-exile such as Mnyele and Wally Serote and in 1979, became a member of the African National Congress. He was made the chief coordinator of the visual art committee in South Africa for assisting artists to attend the Culture and Resistance Conference and Festival in Gaborone. From 1977 up to the time of his arrest he worked and ran art workshops while setting up one of the earliest silk screen and poster making collectives at the Old Mill building in Pietermaritzburg. During the 1980s, he produced T-shirts and posters for the United Democratic Front, while also contributing poetry, essays, and graphics to Staffrider magazine, an important and explicitly non-racial literary production in the 70s and 80s written for the general public about daily life in South Africa. He was later arrested under the Terrorism Act and from 1983 to 1991, was jailed at Robben Island and in Johannesburg. For a period of seven months prior to trial, he was placed in solitary confinement and tortured by the security police. During his time on trial and in prison, he was able to write a book of poetry entitled Baptism of Fire, published in 1984. After his release, he took a job working for the African National Congress and the South African Communist Party. In addition, he released his second work in 1992, Prison Poems.
In addition to his governmental duties, he is a Member of Council of the Robben Island Museum and an Executive Committee Member of the Caversham Centre for writers and artists. He continues to be a patron of the Congress of South African Writers. He is still a practicing artist, with his artwork forming part of the permanent Art collection of the Killie Campbell Collection of the University of KwaZulu-Natal, the Pretoria and Johannesburg Art Galleries, as well as that of numerous private collections.
In November 2017 the suspended head of legal affairs for state company Eskom, Suzanne Daniels, testified before a Parliamentary committee into state capture that Martins had been present at a meeting where Gupta family associate Salim Essa attempted to interfere in Eskom's affairs. Martins responded the next day that he had never been part of such a "phantom coffee tea party meeting" but would have to consult his diary to say where he had been on the day. Martins said he had been introduced to the Gupta family by Lucky Montana, then CEO of state company Prasa. Montana countered that it had been Martins who had introduced him to the Gupta family.
