[4] In Phnom Penh, she adopted the alias Ros Serey Sothea and became a singer for the National Radio service, first performing duets with Im Song Soeum.

[2] She also collaborated with other prominent singers of the era like Pen Ran, Huoy Meas, and Sos Mat, while maintaining an active solo career as well.

She would eventually adopt a more contemporary style incorporating French and American influences, adding western pop/rock instrumentation, as was common in Cambodian music starting in the late 1960s.

[2] Eventually Sothea and her contemporaries were strongly influenced by American radio that had been transmitted to U.S. troops in nearby South Vietnam, inspiring experimentation with American/British rock and soul sounds.

[5][6] Sothea combined her high and clear voice with backing provided by young rock musicians, characterized by prominent electric guitars, drums, and Farfisa organs.

[better source needed] The film Don't Think I've Forgotten also reports that Sothea had a relationship with an officer in the Khmer Republic army and learned to be a paratrooper during the Cambodian Civil War, though her boyfriend is believed to have been killed in combat.

[11] Fans believe that Sothea's unhappy relationships were a primary influence on her singing style and lyrics, indicated by song titles (in translation) like "Don't Be Mad," "Brokenhearted Woman," and "Wicked Husband."

Ros Serey Sothea disappeared during the Khmer Rouge genocide and her exact fate has never been confirmed, with multiple sources making contradictory claims.

Many of Ros Serey Sothea's master recordings were either destroyed by the Khmer Rouge regime in its efforts to eliminate foreign influences from Cambodian society,[12] or deteriorated rapidly in the tropical environment.

Sothea's older sister Ros Saboeut is widely credited with reuniting Cambodia's surviving musicians and bands in the aftermath of the Khmer Rouge era.

[1] Ros Serey Sothea has remained extremely popular posthumously in Cambodia and Cambodian communities scattered throughout the United States, France, Australia, and Canada.

[14] Western listeners were introduced to her work starting in the late 1990s with the release of the Cambodian Rocks bootleg album, followed by the soundtrack to the film City of Ghosts.

[15] Ros Serey Sothea is also profiled extensively in the 2015 documentary film Don't Think I've Forgotten, in which several interview subjects describe her as one of the most important singers in the history of Cambodian popular music.