The son of a shipping manager, Armani intended to become a doctor but left medical school to pursue a career in fashion. Beginning in 1957 he worked as a buyer for the Milan department store La Rinascente. After a seven-year stint in that position, he began to pursue a career in fashion design, training in the atelier of Nino Cerruti. In 1975, with the help of his friend and business partner Sergio Galeotti, Armani launched his own label of ready-to-wear for men and women.

Armani best described his approach to fashion as follows: “I was the first to soften the image of men, and harden the image of women. I dressed men in women's fabrics, and stole from men what women wanted and needed—the power suit.” His androgynous approach rarely disappointed fashion critics, who dutifully appeared each season at shows staged at his 17th-century palazzo on Via Borgonuovo in central Milan. Armani's reputation grew as a result of the popular film American Gigolo (1980), in which actor Richard Gere was featured as the dashing owner of a closetful of tailored Armani clothing. The public developed an increasingly insatiable demand for his minimalist style, and many Hollywood leading ladies became torchbearers for the Armani look at the Academy Awards ceremonies.

Over the years Armani continually added new offerings to his company—introducing perfume, accessories, a jeans line, the lower-priced diffusion line Emporio Armani, sportswear, and a limited-edition line of handmade couture dresses. In 2000–01 the Solomon R. Guggenheim Museum in New York City honoured Armani with a major retrospective of his work.