Boungnang Vorachith joined the Pathet Lao resistance movement in 1952 and worked in the propaganda department of the armed force in Savannakhet. In 1954 he was transferred to the fighting troops. From 1957 to 1961 he studied in Vietnam, after which he returned to Laos back and helped prepare the conquest of the province of Luang Namtha. After the victory in Luang Namtha 1962 he returned to Vietnam and studied at a military academy.
In 1964 he returned to Laos in 1969 and head of the organizing committee of the province of Xieng Khuang. He became deputy commander of the northern front in the province of Luang Prabang in 1972. Here he also joined the coalition in 1974 and became party secretary of defense troops of the neutral city of Luang Prabang. In 1975 he was a political leader of the armed forces of the northern half of the country. Then in 1978 he returned to study political theory to Vietnam. In 1980 he was a political leader of the armed forces, and from 1982 to 1992 he also worked as governor of the province of Savannakhet.
Before he became Prime Minister in 2001, he was Deputy Premier since 1996. In addition, he was from 1996 to 1999 Chairman of the Lao- Vietnamese cooperation committees and from 1999 to 2001 Minister of Finance. On 26 March 2001 he was elected Chairman of the Council of Ministers (Prime Minister) of Laos. On 8 June 2006 he received the former first Deputy Prime Minister Bouasone Bouphavanh followed the Prime Minister. He was already on March 8, 2006 Vice President of the Lao PDR and thus representative of Choummaly Sayasone.
Boungnang Vorachith is married to Khammeung Vorachith and father of three sons and two daughters.