The film starts with Saint Laurent alone and depressed in a hotel room apparently after a night of partying in Paris nightclubs.

Saint Laurent enjoys the nightlife and the endless hours of champagne, pot, and drugs which seem to surround him at every turn.

Saint Laurent's success continues and he forms a long-term same-sex relationship with his business manager, Pierre Bergé, which is profitable to both men financially and in their personal emotional lives.

On one night out of partying, a young male operative named Jacques de Bascher spies out Saint Laurent and approaches him with plainly presented romantic and sexual intentions.

When Saint Laurent wakes up one morning in his hotel room, seemingly alone and dejected, he calls the newspaper journalist whom he had previously declined to interview with, and now present his own sensational tell-all version of his sexual proclivities and his penchant for the Paris nightlife.

The film moves forward in time, showing Saint Laurent in old age living in his opulent Paris apartments surrounded by fine art and expensive fetishist possessions in his collection of exotic leopard skins and other wildlife shown on display throughout his flat.

The website's critics consensus reads, "A well-intentioned but frustratingly diffuse biopic, Saint Laurent proves an ironically poor fit for a look at the life of a fashion icon.

[17] Susan Wloszczyna of RogerEbert.com gave the film 2.5 out of 4 stars, writing, "If you come away remembering anything from this 150-minute movie as it overstays its welcome, it will be individual scenes rather than the overall effect, for that is where Bonello shines.