Shields has stated that her very first encounter with the paparazzi was in the Grand Ballroom of the Waldorf Astoria New York at the age of 12, stating that she "stood like a statue wondering why they were all hired to photograph her" and that she "debuted at the Waldorf".

Shields was raised in the Roman Catholic faith. For her confirmation at age 10, she took the name "Camille". While attending high school, she resided in Haworth, New Jersey, across the George Washington Bridge from Manhattan.

She has two stepbrothers and three half-sisters. When Shields was only five days old, her mother openly stated she wanted her to be active in show business, saying, "She's the most beautiful child and I'm going to help her with her career." Growing up, Shields took piano, ballet, and horse riding lessons.

When Teri announced that she was pregnant, Frank's family paid her a sum to terminate the pregnancy. Teri took the money, but violated the agreement and gave birth to Shields. Frank married Teri, but they were divorced when Shields was five months old.

Her paternal grandmother was Italian noblewoman Marina Torlonia di Civitella-Cesi, who was the daughter of an Italian prince and an American socialite.

According to research by William Addams Reitwiesner, Shields has ancestral links with a number of noble families from Italy, in particular from Genoa and Rome.

Her mother was of English, German, Scotch-Irish, and Welsh descent, while her father had English, French, Irish, and Italian ancestry.

Brooke Christa Shields was born in Manhattan, New York on May 31, 1965, the daughter of actress and model Teri Shields (née Schmon; 1933–2012) and businessman Frank Shields (1941–2003).