Bruni signed with City Models at age 19. Paul Marciano, president and creative director of Guess? Inc., came across her picture among composite cards of aspiring models and chose her to model with Estelle Lefébure in campaigns for Guess? jeans. Bruni subsequently worked for designers and fashion houses such as Christian Dior, Givenchy, Paco Rabanne, Sonia Rykiel, Christian Lacroix, Karl Lagerfeld, John Galliano, Yves Saint-Laurent, Shiatzy Chen, Chanel and Versace.
In 1997, Bruni quit the world of fashion to devote herself to music. She sent her lyrics to Julien Clerc in 1999, based on which he composed six tracks on his 2000 album Si j'étais elle.
In 2002, her debut album Quelqu'un m'a dit, produced by Louis Bertignac, was released in Europe with success in Francophone countries. Three songs from the album appear in Hans Canosa's 2005 American film Conversations with Other Women, the song Le Plus Beau du quartier was used in H&M's Christmas 2006 commercial, and the title track was featured in the 2003 movie Le Divorce and in the 2009 movie (500) Days of Summer. In January 2010, her song 'L'amoureuse' was featured in an episode of NBC's Chuck, 'Chuck vs. First Class'.
In 2004 Carla Bruni wins an EBBA Award. Every year the European Border Breakers Awards (EBBA) recognize the success of ten emerging artists or groups who reached audiences outside their own countries with their first internationally released album in the past year.
In 2005, she wrote the lyrics for ten out of twelve songs for Louis Bertignac's new album Longtemps, and performed two duets with him on the album, Les Frôleuses and Sans toi. In 2006, Bruni recorded 'Those Little Things', an English-language translation of the Serge Gainsbourg song 'Ces petits riens' for the tribute album Monsieur Gainsbourg Revisited. She took part in the opening ceremony of the 2006 Winter Olympics in a parade paying tribute to the Italian flag.
Her second album, 'No Promises' containing poems by William Butler Yeats, Emily Dickinson, W. H. Auden, Dorothy Parker, Walter de la Mare, and Christina Rossetti, set to music, was released in January 2007.
She continued recording after her marriage. She released her third album Comme si de rien n'était on 11 July 2008. The songs are self-penned except for one rendition of 'You Belong to Me' and another song featuring Michel Houellebecq's poem La Possibilité d'une île set to music. Royalties from the album will be donated to unidentified charitable and humanitarian cause.
Bruni sang for Nelson Mandela's 91st birthday on 18 July 2009 at Radio City Music Hall in New York City.
In September 2009, she recorded a duet with Harry Connick, Jr. for the French edition of his album Your Songs. They sang the Beatles song 'And I Love Her'. The album was released in France on 26 October 2009.
Following months of speculation, in a television interview broadcast on 23 November 2009, Bruni revealed that she had accepted a role in a forthcoming Woody Allen film. She admitted her reasoning for embarking on the Paris production; 'I'm not an actress at all. Perhaps I'll be completely hopeless but I can't miss an opportunity like this one. When I'm a grandmother I'd like to be able to say I made a film with Woody Allen.' The film, Midnight in Paris, was released in 2011; Bruni appeared as a guide at the Musée Rodin, who discusses sculptor Auguste Rodin with the leading characters.
In September 2010, she contributed a cover of David Bowie's 'Absolute Beginners' to the War Child charity record We Were So Turned On: a tribute to David Bowie (Manimal Vinyl). They also released the track as a split 7" vinyl split with UK legends, Duran Duran.