The son of a landowning farmer, Saloth Sar was sent at age 5 or 6 to live with an older brother in Phnom Penh, where he was educated. A mediocre student, he failed the entrance examinations for high school and so instead studied carpentry for a year at a technical school in Phnom Penh. In 1949 he went to Paris on a scholarship to study radio electronics. There he became involved with the French Communist Party and joined a group of young left-wing Cambodian nationalists who later became his fellow leaders in the Khmer Rouge. In France he spent more time on revolutionary activities than on his studies. His scholarship was cut short after he failed examinations, and he returned to Phnom Penh in 1953.

Pol Pot taught at a private school in Phnom Penh from 1956 to 1963, when he left the capital because his communist ties were suspected by the police. By 1963 he had adopted his revolutionary pseudonym, Pol Pot. He spent the next 12 years building up the Communist Party that had been organized in Cambodia in 1960, and he served as the party's secretary. An opponent of the Norodom Sihanouk government and of the military government of General Lon Nol, he led the Khmer Rouge guerrilla forces in their overthrow of Lon Nol's regime in 1975. Pol Pot was prime minister of the new Khmer Rouge government from 1976 until he was overthrown by invading Vietnamese in January 1979. It is estimated that from 1975 to 1979, under the leadership of Pol Pot, the government caused the deaths of more than one million people from forced labour, starvation, disease, torture, or execution while carrying out a program of radical social and agricultural reforms.

Following the Vietnamese invasion of his country, Pol Pot withdrew to bases in Thailand to lead the Khmer Rouge forces against the new Hanoi-supported government in Phnom Penh, which refused to consider peace negotiations as long as he remained at the head of the party. Although ostensibly removed from the military and political leadership of the Khmer Rouge in 1985, he remained a guiding force in the organization, which continued its guerrilla campaign into the 1990s, though with diminishing intensity. By 1997 the Khmer Rouge were in deep decline, their ranks riddled by desertions and factionalism. In June of that year Pol Pot was forcibly ousted from the organization's leadership and placed under house arrest by his colleagues, and in July he was convicted of treason. Pol Pot died of natural causes in 1998.