Laetitia's mother, Line Blin, is from Normandy. Her father, Dominique Casta, is from Corsica. She has an older brother, Jean-Baptiste, and a younger sister, Marie-Ange.

On October 19, 2001, she gave birth to her daughter Sahteene. The father is her former boyfriend Stéphane Sednaoui. Casta is engaged to Italian actor Stefano Accorsi. They are expecting a child in September 2006.

Time Magazine once named her one of the top ten most influential people of the year.

Casta's career reportedly began when she was discovered by a photographer during a family holiday in her father's native Corsica, at age 15.

Casta is a supermodel and the official face of L'Oréal. She has graced the covers of Victoria's Secret and featured in Guess? Jeans campaigns. She has also appeared in three consecutive Sports Illustrated swimsuit editions, Rolling Stone, Pirelli Tires Calendar, L'Oreal promotions, and Victoria's Secret. She also had a close relationship with designer Yves St. Laurent, whose outfits she would regularly wear at public appearances.

Laetitia Casta has graced over 100 magazine covers and has been credited, along with Tyra Banks, with bringing back the ideal of a voluptuous model.

Laetitia & child.The native of Normandy, who was raised in Corsica, whose curvy physical features have been a subject of discussion in the world of fashion, spent her childhood in Normandy, has stated in an interview with ELLE magazine: "I tell people that my breasts are 'Made in Normandy,' from butter and creme fraîche!" Laetitia says that she only needs to be in the mountain with some cheese and some bread to be happy.

In 1999, the French government decided that Casta would be the new model for the bust of Marianne, a symbol of the French Republic, which stands outside every French town hall. She succeeded model Inès de la Fressange in this role. Furthermore, Casta's image is scheduled to appear on French postage stamps.

In the past few years, Casta has made forays into Francophone film and television productions, including Astérix et Obélix contre César, a live-action film of the Astérix world in which she plays a potential love interest for Obélix, portrayed by Gérard Dépardieu.