Lelong did not actually create the garments that bore his label. "He did not design himself, but worked through his designers," wrote Christian Dior, who was a member of the Lelong team from 1941 until 1946, during which time he created the collections in collaboration with Pierre Balmain. "Nevertheless," Dior continued, "in the course of his career as couturier his collections retained a style which was really his own and greatly resembled him." Other designers who worked for Lelong included Nadine Robinson and Hubert de Givenchy.
Among Lelong's clients were Marie Duhamel, Colette, Jeanne Ternisien (wife of the banker Georges Nelze), the Duchess de la Rochefoucauld, Greta Garbo, Gloria Swanson, Colette, and Rose Kennedy.
His first wife, whom he divorced on 16 July 1927, was Anne-Marie Audoy.
He married on 10 August 1927, as his second wife, Princess Natalie Paley (1905-1981), who had worked as a saleswoman in the Lelong perfume department. She was a daughter of Grand Duke Paul Alexandrovich of Russia and his morganatic wife, Olga Karnova. They divorced in 1937.
Lelong's third wife, who outlived him, went on to marry the French journalist Maurice Goudeket, the widower of Colette.