When Montenegro was 10 years old she landed her first acting part in the TV series Juguemos A Cantar. In 1989 she joined the group Garibaldi. During the mid '90s she began to appear in soap operas and left Garibaldi to pursue a solo career. By 1996 she released her debut album Son del Corazón.
In 2001 Montenegro reemerged into the music scene by the hand of former husband and executive music producer Jorge Reynoso, after 6 months of recording with the Music production of Rudy Perez they released her second album Desahogo. The album produced the hit single, a cover of Yolandita Monge’s Quitame Ese Hombre. The Hit single spent 13 consecutive Weeks at Number 1 on the Hot Latin Track of Billboard. With the success of the album "Desahogo" Pilar Montenegro won multiple awards, including 4 Latin Billboard Awards. As reported by Telemundo's Suelta la Sopa on August 5, 2016, Pilar suffers from depression which may explain some questionable behavior she exhibited over the past two years.