They say you cannot choose your family, but you can choose your friends. Alexandre Mattiussi would like you to choose him—or rather his label AMI, a contraction of his initials and the last letter of his name (it means “friend” in French). The 39-year-old designer, an alum of Dior, Givenchy and Marc Jacobs, launched his first menswear collection in January 2011¹ with the promise of making fashion more approachable, and has since become a global player with stores in Paris, London, Tokyo, Hong Kong, Beijing and Chengdu.² Now, as the Parisian house ventures into womenswear, Mattiussi maintains a down-to-earth approach to his craft and, he insists, one goal: to be happy.

Does “friendly fashion” sum up your brand’s philosophy?
Yes, as soon as I realized that my initials formed...