Born in Samrong Young, Cambodia, Ngor trained as a surgeon and gynecologist. He was practicing in the capital, Phnom Penh, in 1975 when Pol Pot's Khmer Rouge seized control of the country and proclaimed it Democratic Kampuchea. He never remarried.

In 1988, he wrote Haing Ngor: A Cambodian Odyssey , describing his life under the Khmer Rouge in Cambodia. In the second edition of Survival in the Killing Fields, Roger Warner, Ngor's co-author, adds an epilogue telling the story of Ngor's life after winning the Academy Award.

The "Dr. Haing S. Ngor Foundation" was founded in his honor in 1997 to assist in raising funds for Cambodian aid. As part of his humanitarian efforts, Ngor built an elementary school and operated a small sawmill that provided jobs and an income for local families. Ngor's niece, Sophia Ngor Demetri, who testified at the trial of his murderers and with whom he arrived to the U.S., is the current President of the Foundation.

Ngor, despite having no previous acting experience, was cast as Dith Pran in The Killing Fields , a role for which he later won three awards, including a Golden Globe Award and an Academy Award for Best Supporting Actor. Ngor also appeared in other movies and TV shows, most memorably in Oliver Stone's Heaven & Earth and the Vanishing Son miniseries. He also appeared in the Hong Kong film Eastern Condors, which was directed by and starred Sammo Hung. He also appeared in a supporting role in the 1989 Vietnam War drama, The Iron Triangle. He guest-starred in a two-episode storyline on the acclaimed series China Beach (episodes "How to Stay Alive in Vietnam 1 & 2 ") as a wounded Cambodian POW who befriends Colleen McMurphy while under her care. He also guest-starred in an episode of Miami Vice called "The Savage / Duty and Honor".

The Dr. Haing S. Ngor Foundation was organized in 1990 by Ngor and Jack Ong. The two actors met in 1989 while filming "The Iron Triangle" and soon after, Pastor Ong's church (Venice Christian Community in Venice, CA) launched Project Cambodia to raise funds to care for orphans and help rebuild the devastated country's infrastructure. Project Cambodia was the original foundation for The Dr. Haing S. Ngor Foundation, which was incorporated in 1997 after Ngor's homicide (Feb. 25, 1996) as a 501 (C) (3) charitable organization. The goals of the Foundation include preserving the legacy of Ngor's accomplishments and human rights endeavors as well as the promotion of Cambodia's history and culture through education, activism and the arts. Ngor's niece, Sophia Ngor Demetri, who testified at the trial of his murderers and whom he brought to the U.S., is the current President of the Foundation; Ong serves as Executive Director.

On February 25, 1996, Ngor was shot dead outside his home in Chinatown , in downtown Los Angeles, California. Ngor was buried at Rose Hills Memorial Park in Whittier, California. Many Cambodians claimed they had a stake in his estate, with one woman claiming he had married her after coming to the United States. Most of Ngor's Cambodian assets went to his brother, Chan Sarun, while his American assets were used up in legal fees staving off claims to his estate.

Charged with the murder were three reputed members of the "Oriental Lazy Boyz" street gang who had a prior history of snatching purses and jewelry. They were tried together in the Superior Court of Los Angeles, though their cases were heard by three separate juries. Prosecutors argued that they killed Ngor because, after handing over his gold Rolex watch willingly, he refused to give them a locket that contained a photo of his deceased wife, My-Huoy. Defense attorneys suggested the murder was a politically motivated killing carried out by sympathizers of the Khmer Rouge but offered no evidence to support this theory.

Kang Kek Iew, a former Khmer Rouge official on trial in Cambodia, claimed in November 2009 that Ngor was murdered on Pol Pot's orders, but U.S. investigators did not find him credible.

Some criticized the theory that Ngor was killed in a bungled robbery, pointing to $2,900 in cash that had been left behind and the fact that the thieves had not rifled his pockets. Why the thieves would have demanded his locket has never been answered; Ngor typically wore the locket next to his skin under his clothing, so it would not have been in plain sight. As of 2003, the locket has not been recovered.

All three were found guilty on April 16, 1998, the same day Pol Pot's death was confirmed in Cambodia. Tak Sun Tan was sentenced to 56 years to life; Indra Lim to 26 years to life; and Jason Chan to life without parole. In 2004, the U.S. District Court for the Central District of California granted Tak Sun Tan's habeas corpus petition, finding that prosecutors had manipulated the jury's sympathy by presenting false evidence. This decision was reversed, and the conviction was ultimately upheld by the United States Court of Appeals for the Ninth Circuit in July 2005.

After the release of The Killing Fields , Ngor had told a New York Times reporter, "If I die from now on, OK! This film will go on for a hundred years."

Dith Pran, whom Ngor portrayed in The Killing Fields , said of Ngor's death, "He is like a twin with me. He is like a co-messenger and right now I am alone."

Year	Film	Role	Other notes
1984	''The Killing Fields (film)|The Killing Fields''	Dith Pran	(as Dr. Haing S Ngor) Academy Award for Best Supporting Actor BAFTA Award for Best Actor in a Leading Role BAFTA Award for Best Newcomer Golden Globe Award for Best Supporting Actor - Motion Picture Boston Society of Film Critics Award for Best Actor|BSFC Award for Best Actor
1986	''Dung fong tuk ying (Eastern Condors)''	Yeung Lung		-	rowspan=2|1989	''Vietnam War Story: The Last Days''	Major Huyen	segment "The Last Outpost"
''The Iron Triangle (film)|The Iron Triangle''	Colonel Tuong, NVA		-	rowspan=2|1990	''Vietnam, Texas''	Wong
''Last Flight Out''	Pham Van Minh		-	1991	''Ambition''	Tatay		-	rowspan=3|1993	''My Life (film)|My Life''	Mr. Ho		-	''Heaven & Earth (1993 film)|Heaven & Earth''	Papa		-	''Fortunes of War (1993 film)|Fortunes of War''	Khoy Thuon		-	1994	''The Dragon Gate''	Sensei		-	1996	''Hit Me''	Billy Tungpet		-

• Ngor, Haing with Roger Warner. A Cambodian Odyssey. Macmillian Publishing Company, 1987. ISBN 0-02-589330-0.

• Ngor, Haing with Roger Warner. Survival in the Killing Fields. Carroll & Graf Publishers, 2003. ISBN 0786713151.

• Haing Ngor Foundation website

• Yahoo! Biography

• CNN story on his death

• Los Angeles Times article on his murder