The Yves Saint-Laurent foundation lent the filmmakers 77 actual pieces from their archive for use in the film. The actors and models who wear these authentic Yves Saint Laurent clothes had to wear special underwear underneath the outfits, so that the clothes never touched their skin. Conservators from the foundation were present to make sure the historic, irreplaceable garments were correctly handled and stored.
When Saint Laurent debuts his first collection under his own label in 1962, the clothes seen are all real garments from the actual collection. The models who appear in the fashion show had to be cast to fit the existing garments because the clothes could not be altered or tailored to fit them.
Madeline Fontaine recreated the famous Saint Laurent-designed Dior wedding dress by finding a vintage wedding dress at a flea market and rebuilding it.
Pierre Bergé, who is played in the film by Guillaume Gallienne, worked closely with director Jalil Lespert and gave the crew extensive access to his archives.