Sarah Asher Geronimo was born to Delfin Geronimo, used to a beauty salon in her house in Sta. Cruz, Manila. Sarah is the third of four children with siblings Johna Rizzi, Sunshine Grace and Ezekiel Gabriel.
Geronimo's first appearance on the stage is located in a mall, when they two years old. Sarah sang "Pasko Na naman" with Pinky Marquez and Richard Reynoso. It was part of a children's show, Pen-Pen de Sarapen, from 1992 to 1994, Ang TV from 1995 to 1996 and then from 1996 to 1997. She was one of the performers during the 1995 visit of Pope John Paul II
Star for a night, which was developed by Regine Velasquez, was the singing competition, where they are on 1 March 2003, at the age of 14 years.