Ngcobo was born near Melmoth, Zululand. He was educated to secondary school level at Inkamane. In 1953 he attended Ndaleni Educational Training Centre, Natal, studying there from 1953 to 1954.
He worked as a teacher at Glencoe and Loram Secondary School in Durban, as well as at Isibonelo High School and Mzuvele Secondary School, before becoming an Inspector of Education for the KwaZulu-Natal Department of Education and Culture in Ulundi.
He was both a sculptor of busts and portraits, using indigenous hardwoods, and a painter of primarily impressionistic group compositions. In both media his work was based on a mixture of tribal mythology and urban life. He won the Gold Medal for Painting at the Republic Art Festival in Bloemfontein in 1961; his work was shown on the 1963 Art - South Africa - Today exhibition at the DAG. He was on the Organising Committee of the 1963 and 1965 Art - South Africa - Today Exhibitions. He exhibited in group shows in South Africa and Lesotho and in 1962 he was the first black artist to hold a solo exhibition at the Durban Art Gallery.