[1][2][3] Born near Paris in 1943 to a modest family, Demarchelier spent his childhood in Le Havre, Normandy, with his mother and four brothers.

Demarchelier shot international advertising campaigns for Dior, Louis Vuitton, Celine, TAG Heuer, Chanel, Donna Karan, Yves Saint Laurent, Tommy Hilfiger, Carolina Herrera, Moschino, Vera Wang, Elizabeth Arden, H&M, Sam Edelman, Zara, Max Azria, Express, Longchamp, Blumarine, Lacoste, Ann Taylor, Calvin Klein, and Ralph Lauren.

From the late 1970s on, Patrick Demarchelier photographed the covers for nearly every major fashion magazine including American, British and Paris Vogue.

He photographed many advertising campaigns, including Farrah Fawcett shampoo in 1978, the Brooke Shields doll in 1982, Lauren by Ralph Lauren, Cutty Sark, and a Calvin Klein ad with Talisa Soto and Giorgio Armani, Chanel, GAP, Gianni Versace, L'Oréal, Elizabeth Arden, Revlon, Lancôme, and Gianfranco Ferré.

He appeared in a cameo in the film version of Sex and the City (2008), where he can be seen taking pictures during Carrie Bradshaw's fashion shoot for Vogue.