Abécassis was born in Strasbourg. Her first book, Qumran, was released in 1996 after three years of research, and has been translated into eighteen languages. Her second title, L'Or et la cendre, details the historical and mysterious murder of a Berlin theologian. Murder also figures high in her 1998 work on the philosophical origins of homicide entitled Petite Métaphysique du meurtre. Her next novel, La Répudiée, a finalist for the Grand Prix du roman de l'Académie française and for the Prix Fémina, was the inspiration for Amos Gitai's film Kadosh. To research this book, Abécassis spent six months in the very orthodox Mea Shearim section of Jerusalem.
Her book Clandestin (2003) was one of twelve books chosen for the Prix Goncourt.
In 2012, she performs a musical version of Sepharade, after her eponym book, with French baritone David Serero in Paris.