Fairuz was born Nouhad Haddad into a working-class, Christian Orthodox family in the town of Jabal Al Arz; she grew up in the modest Zuqaq-el-Blat district of Beirut. Her talents were first recognized by Mohammad Fleifel of the Lebanese Radio Station. Fairuz first recorded nationalist songs for the radio and her talent was instantly recognized, primarily by the prominent Lebanese musician Halim Al-Rumi, who was the one to give Nouhad Haddad the name of Fairuz. Al-Rumi later convinced Fairuz's conservative father to enroll her at the National Music Institute in Beirut. She began her musical career as a choir singer in the Lebanese Radio Station (al-Iza'a al Loubnaniah).

Shortly thereafter Fairuz began a long and fruitful collaboration with Assy and Mansour Rahbani, who wrote and composed most of her songs. (Mansour wrote the lyrics and Assy, whom Fairuz married in 1954 at age 19, composed the music). They began to receive invitations to travel to Cairo, Damascus, and other Arab cities to perform.

Fairuz's early recordings were an innovative mixture of Arab instruments and musical idioms with European instruments, such as violins, and dance rhythms, combining Fairuz's distinct vocal timbre with lyrics that expressed nostalgia for Levantine village life. She also sang several nationalist songs for Lebanon, the Palestinians, and Syria.

In 1969, Fairuz’s music was banned in Lebanon by order of the government because she refused to sing at the honor of the Algerian president Howari Boumedianne. Fairuz also starred in three motion pictures produced in the 1960s. One of the films, Safarbarlek, dealt with the Ottoman occupation of Lebanon and the area, prompted an official objection by Turkey.

In 1971, Fairuz and the Rahbani brothers made a successful tour of the United States followed by visits to many other countries. Fairuz performed in Royal Albert Hall in London, Carnegie Hall in New York and the Paris Olympia. "Fairuz in America", a documentary about her US tour, was the highest rated television show in the Arab world when it was broadcast.

Fairuz was also deeply affected by the death of one of her children and the disability of another. Ziad is her eldest son and is a notable composer and playwright and Rima, her daughter, is a film director.

During the Lebanese Civil War (1975-1990), Fairuz remained in Lebanon, even though she could have easily left. While she ceased performing, she made several international tours, performing to huge crowds around the world. Her neutral stance in the civil war made of her a national symbol for all the Lebanese, regardless of their sectarian identity. In 1998, she appeared again at the Baalbek festival after twenty years of absence.

Later recordings featured jazz-tinted compositions, some of which were written by Ziad Rahbani.

Fairuz, 70 years of age, is considered the most popular and respected living Arab singer.