French president Nicolas Sarkozy and his wife Carla Bruni, who modelled for Saint Laurent in the 1990s, attended the service yesterday afternoon at the Eglise Saint-Roch in Paris.
Saint Laurent's long-time partner Pierre Berge paid a moving tribute to the designer. He said: "For 50 years our paths never separated. Leaving you, Yves, I shall tell you of my admiration, my deep respect and my love."
Berge was joined by Saint Laurent's mother, Lucienne Saint Laurent.
Catherine Deneuve, the actress and a former muse of Saint Laurent, read a Walt Whitman poem at the Mass, which was relayed to the crowds outside via a giant screen.
Other guests included Kenzo Takada, Valentino, Hubert de Givenchy, Christian Lacroix, John Galliano, Vivienne Westwood, Jean Paul Gaultier and Sonia Rykiel.
Saint Laurent, who died of a brain tumour on Sunday, will have his ashes spread in a botanical garden close to the villa in Marrakech, Morocco, where he spent much of his time.