Ung Huot was born in 1945 in Kandal Province. He studied accounting and finance and was awarded a scholarship to study in Australia in 1971, as Cambodia’s civil war was beginning. He received a Master of Business Administration from the University of Melbourne, and became an Australian citizen. He settled in Melbourne and proclaimed himself a leader of the Cambodian expatriate committee in that city. He moved back to Cambodia in 1991 as the communist government was falling, and became a high-ranking official in the FUNCINPEC party. He became the Minister of Education, and in 1994 he left that post to become foreign minister.

In July 1997, FUNCINPEC leader Norodom Ranariddh, who was serving as first prime minister, was deposed by second prime minister Hun Sen of FUNCINPEC’s rival and coalition partner, the Cambodian People’s Party. Hun invited Ung to become first prime minister to replace Ranariddh. Ranariddh’s father, King Norodom Sihanouk at first refused to recognize the arrangement, but Ung became first prime minister in August 1997 after being elected by Parliament. When some people within FUNCINPEC accused Ung of being a puppet, he was forced to leave FUNCINPEC and form his own party, the Reastr-Niyum Party (Populist Party). In the 1998 elections, the Reastr-Niyum Party did not gain any seats in Parliament, and Ung was forced to resign from the posts of first prime minister and foreign minister, leaving Hun to be the sole prime minister.