Born in Lyon, France, Cret was educated at that city's École des Beaux-Arts, then in Paris, where he studied at the atelier of Jean-Louis Pascal.

He enlisted and remained in the French Army for the duration of the war, and was awarded the Croix de Guerre and made an officer in the Legion of Honor.

Some of Cret's work is remarkably streamlined and forward thinking, and includes collaborations with sculptors such as Alfred Bottiau and Leon Hermant.

In the late 1920s, he was brought in as design consultant on Fellheimer and Wagner's, which is the present-day Cincinnati Union Terminal, built between 1929 and 1933 during Art Deco's peak of popularity in architectural style in the U.S.

Cret's contributions to the railroad industry included designing the side fluting on Burlington's Pioneer Zephyr, which debuted in 1934, and the Santa Fe's Super Chief passenger cars, which were completed in 1936.

Cret taught in the Department of Architecture at the University of Pennsylvania for over 30 years, and designed the overall design for the Ellen Phillips Samuel Memorial in Fairmount Park, the Rodin Museum in Philadelphia, the master plan for the University of Texas at Austin, the Benjamin Franklin Bridge, one of the primary bridges across the Delaware River between Philadelphia and South Jersey, and the Duke Ellington Bridge in Washington, D.C. Cret's students included Louis Kahn, who studied under him at the University of Pennsylvania and worked in Cret's architectural office in 1929 and 1930.

[13] Following Cret's death in 1945, his four partners assumed the practice under the partnership Harbeson, Hough, Livingston & Larson, which for years was referred to by staff members as H2L2.