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 have one son together, Orlando, born on September 24, 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 was the official face of L'Oréal, Dior, and Chanel. She has appeared in and on the cover of Victoria's Secret catalogs, ELLE magazine, and Vogue magazine. She was featured in Guess? Jeans and Tommy Hilfiger ad campaigns. She also appeared in three consecutive Sports Illustrated swimsuit editions, Rolling Stone, and a Pirelli Tires Calendar.
She once had a close relationship with designer Yves St. Laurent, whose outfits she would regularly wear at public appearances.
Laetitia Casta has appeared on over 100 magazine covers and has been credited, along with Tyra Banks, and a few others, with bringing back the notion of the voluptuous models.
Casta, whose curvaceousness has been a subject of discussion in the world of fashion, spent her childhood in Normandy and has stated in an interview with ELLE magazine: "I tell people that my breasts are 'Made in Normandy,' from butter and crème fraîche!" Casta has also said that she only needs to be in the mountains with some cheese and some bread to be happy.
In 1999, Casta came out first of a national survey ordered by the Association des Maires de France to decide who should be the 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. Shortly thereafter a mini-scandal shook France, after it was publicized that Casta had relocated to London. Although she claimed that her move to London was motivated by practical professional reasons, the magazine Le Point, among others, suggested that she was trying to escape taxes, "following 250,000 other money-making Frenchmen who moved to the United Kingdom."
In the past few years, Casta has made forays into Francophone film and television productions, including Astérix et Obélix contre César (known as Astérix and Obélix vs. César in English language versions), a live-action film of the Astérix world in which she plays a potential love interest for Obélix, portrayed by Gérard Dépardieu.
Casta was also prominently featured in the music video for the Chris Isaak song "Baby Did a Bad, Bad Thing".