Educated at Manzini Central School, then St Joseph's Mission School at Mbuluzi and finally at Matsapa Swazi National High School.
For four years he taught in schools at Nkambeni and Mhlambanyati, from 1954 to 1958, then he crossed into South Africa to work in the Johannesburg gold mines and study at night. In February 1960 he returned to Swaziland and went into business as a livestock dealer.
His campaign against adult illiteracy began in December 1961 when he arranged a public meeting and formed a committee which established the Sebenta National Institute. Initially supported by private donations later aided by the Swaziland government and UNESCO the Institute organised volunteers to go to villages teaching peasants to read and write. In 1965 in a pause from politics Nxumalo was Director of the Sebenta National Institute and in 1971, even though then a cabinet minister, he became chairman and launched a seven-year programme aimed at eliminating adult illiteracy completely.
From 1965 to 1967 he was a King’s envoy, journeying to many countries in Africa as well as Europe, Asia and America. On April 20, 1967, he was elected to Parliament as an Imbokodvo candidate and became a junior minister as Minister of State for Finance, Commerce and Industry.
At independence on September 6, 1968, he joined the cabinet as Minister of Commerce, Industry and Mines. He was the Swaziland delegate to the meeting of the Organisation of African Unity at Addis Ababa in 1971. He led the delegation for the important mineral negotiations in England in June 1972. After a successful election campaign he became Minister for Industry, Mines and Tourism in the cabinet formed on June 2, 1972.
His political career started when he founded the Swaziland Democratic Party in 1962. The following year his cousin Dr Allen Nxumalo joined forces and became President of the SDP while he ran the party organisation as Secretary General. He took part in the constitutional conferenceheld in London in January and February 1963.
After defeat in the first elections for the Legislative Council in June 1964 he left the Swaziland Democratic Party in October 1964. The party was dissolved in April 1965. He wanted more democratic freedom and a Swaziland moving with the rest of black Africa, free from white South African influence. In the end he came to the conclusion that these aims could best be realised by joining the Imbokodvo National Movement and working from inside.
One of the outstanding politicians in southern Africa with all the talents in administration and negotiation necessary to lead his country some day as Prime Minister. After a brief unsuccessful career as an opposition democrat he decided that since he could not beat the ruling Imbokodvo party he had better join them. Within a short time he was a leading political figure as party treasurer and a senior member of the cabinet.