Seng was a Khmer Krom. Born in commune of Tri Tôn, Châu Đốc Province, Cochinchina (in present-day An Giang Province, Vietnam). He was a cousin of Chau Sen Cocsal Chhum. Educated in France, in Paris, he became a communist. On his return to Cambodia, he had become Norodom Sihanouk's private secretary. He joint the Sangkum on 13 April 1957 together with Hou Yuon and Hu Nim. In the same year, Chau Seng was elected a member of National Assembly. After that he was appointed under-secretary, and later secretary of state for education. Seng made a national attempt at Cambodianization, however it was failed.
After the Cambodian coup of 1970 in which Sihanouk was ousted by Lon Nol, Chau Seng served as the Minister for Special Missions of the GRUNK government, the Beijing-based government-in-exile that was formed as a coalition between Sihanouk and the communists.
- Philip Short, Pol Pot: Anatomy of a Nightmare, p. 129
- David M. Ayres. Anatomy of a Crisis: Education, Development, and the State in Cambodia, 1953-1998. University of Hawaii Press. p. 43-44. ISBN 0-8248-2238-2.
- GRUNK - Place de Barcelone
- "Pol Pot's Daughter Marries in Former Stronghold". Cambodian Daily. March 17, 2014.
- David M. Ayres. Anatomy of a Crisis: Education, Development, and the State in Cambodia, 1953-1998. University of Hawaii Press. p. 108. ISBN 0-8248-2238-2.