Gemser left Indonesia in 1955, at the age of four, and moved with her parents to the Netherlands. She grew up in the Dutch city of Utrecht, where she attended the MULO Regentesseschool high school. After that, she attended the Artibus Art School in Utrecht, where she specialised in fashion design.
After modelling in various magazines in the Netherlands and Belgium, in 1974 she moved to Italy to star in the erotic film Amore libero - Free Love. The film was a box office success and launched the career of Gemser. She played one of the masseuses in the 1975 film Emmanuelle 2 (aka Emmanuelle, The Joys of a Woman), and later that year took the starring role in Bitto Albertini's Black Emanuelle. She starred in a number of further Black Emanuelle films in the 1970s.
She starred as Laotian Actress Keo Sirisomphone in Michael Landon's 1983 American television film, Love is Forever, in which she was credited as Moira Chen. Gemser continued to make films, at times working with her actor husband, Gabriele Tinti. In the 1990s, she retired from films to work on costume designing for film.
