Hayslip was the youngest of seven children born and raised in Ky La, now Xa Hao Qui, a village in central Vietnam, just south of Da Nang. American helicopters landed in her village when she was 12 years old. At the age of 14, she endured torture in a South Vietnamese government prison for "revolutionary sympathies". After being released, she had fallen under suspicion of being a government spy, and was sentenced to death by the Viet Cong. However, instead of killing her, her executioners raped her.
She fled to Saigon, where she and her mother worked as housekeepers for a wealthy Vietnamese family, but this position ended after Hayslip's affair with her employer and subsequent pregnancy. Hayslip and her mother fled to Da Nang, and by the age of 16, Hayslip was supporting both her mother and an infant son, Hung (whom she would later rename Jimmy), while unmarried and working in the black market and as an occasional drug courier, and once even as a prostitute.
She worked for a while as a nurse assistant in a Da Nang hospital and began dating Americans. She had several disastrous, heartbreaking affairs before meeting and marrying an American civilian contractor named Ed Munro in 1969. Although he was more than twice her age, she had another son with him, Thomas. Hayslip moved to San Diego, California the following year to join him, and briefly supported her family as a homemaker. In 1973, he died of emphysema, leaving Le Ly a widow at age 24.
In 1974, she married Dennis Hayslip. Her second marriage, however, had never been a happy one. Dennis was a heavy drinker, clinically depressed, and full of rage. Her third and youngest son, Alan, was fathered by Dennis and born on her 26th birthday. The couple filed for divorce in 1982 after Dennis committed domestic violence. Shortly thereafter, he was found dead in a parked van outside a school building. He had established a trust fund, however, that left his wife with some money, and he had insurance that paid off the mortgage of the house. With this money, she began a series of investments in real estate, the stock market, and small businesses that would eventually make her quite well off.
Her first book, A Vietnamese Woman's Journey from War to Peace (Doubleday, 1989), tells the story of her somewhat peaceful early childhood and war-torn adolescence. The nonlinear structure alternates between the narration of her life in Vietnam as a child and her first return to Vietnam and her family in 1986. The two stories are interwoven to show the circular nature of Hayslip's journey, both her physical journey and her emotional one.
Her second memoir, Child of War, Woman of Peace (Doubleday, 1993), continues the same themes in a more linear narrative. Set in the United States during the final years of the Vietnam War, Hayslip must deal with an alien culture and the idea that she may never be able to return to her family and native country, where she is viewed as a traitor. Her tenacity and business skills help her profit, and eventually, she is able to found the East Meets West Foundation, a charitable group dedicated to improving the health and welfare of the Vietnamese, as well as creating self-sufficiency of the people to run the programs started in Vietnam by East Meets West. This memoir documents not only her struggles and successes in the United States but also her growing need to help heal the pain caused by the Vietnam War in both the United States and in Vietnam.
The 1993 film Heaven & Earth, directed by Oliver Stone, is based on her life. She also has a cameo appearance in the film.
Le Ly Hayslip founded two charitable organizations: East Meets West Foundation and Global Village Foundation for humanitarian and emergency assistance to the needy in Vietnam and some other countries of Asia.