Bounnhang Vorachit joined the Pathet Lao resistance movement in 1951 and worked in the propaganda department of the armed forces in Savannakhet.

Here he also joined the coalition in 1974 and became party secretary of the defence forces of the neutral city Luang Prabang.

In 1981, he became political leader of the armed forces, and in the same year up to 1991, he also worked as Governor of Savannakhet Province until 1996, when he became Deputy Prime Minister.

He underwent military training there and, after taking part in founding the Lao People's Democratic Republic in 1975, he studied socialist thought there.

At the 11th congress of the Lao People's Revolutionary Party (2021), he stepped down as General Secretary in favor of Thongloun Sisoulith.