In 1959, Ngwenya’s works were exhibited publicly for the first time as part of a group show and two years later at the age of 25, he had his first solo exhibition. The show included the work Juizo Final (Final Judgment), which depicted the brutality of life under colonial rule. Much of Ngwenya’s artistic work from this period to the early 1990’s reflected the political turmoil of Mozambique. It was not until multiparty elections in 1994 that Ngwenya’s work began to depict a more hopeful phase in Mozambique’s history. His work became known to the general public thanks to an art fair held in 1959, and then with his solo exhibition held two years later. The publication of his poems in the literary journal Black Orpheus and in an Anthology of Modern Poetry from Africa in 1963 brought him recognition.
In 1964, he joined the nationalistic FRELIMO guerrilla movement, was detained by the Portuguese secret police of the Estado Novo regime, and was jailed for 18 months. He received a Gulbenkian Foundation grant in 1971, and studied engraving and ceramics in Portugal, during which time his art works were exhibited in Mozambique and in Lisbon.
After Mozambique independence and the Carnation Revolution of April 1974, Ngwenya openly rejoined FRELIMO, now the single-party communist organization that was ruling the new country, and worked in political mobilization events and alphabetization campaigns. In 1979 he participated in the exhibition Moderne Kunst aus Afrika (organized in West Berlin), part of the first Horizonte-Festival der Weltkulturen.
After 1981 he worked full-time as an artist, exhibiting throughout Africa, and is in the collection of the National Museum of African Art in Washington, DC.
In addition, executing the FRELIMO and UNESCO murals and a large mural in the stairwell of the original Africa Centre, London in King Street, Covent Garden. He was a founder of the Mozambican Peace Movement and awarded the Nachingwea Medal for his Contribution to Mozambican Culture, and was made a Grande Oficial da Ordem do Infante D. Henrique.
In 1997 he was named a UNESCO Artist for Peace and received a Prince Claus Award. He was awarded a degree honoris causa by the University of Évora in 2010.
He died at the age of 74, on 5 January 2011 in Matosinhos, northern Portugal, after a long illness.