Bailey developed a love of natural history, and this led him into photography. Studies was nothing for him, so when he finally decided on a career in photography, he was unable to obtain a place at the London College of Printing. Instead, he became a second assistant to David Ollins, in Charlotte Mews as studio dogs body, before he became a photographic assistant at the John French studio in 1960. He was a photographer for John Cole's Studio Five, before being contracted as a fashion photographer for British Vogue magazine later that year.
Along with Terence Donovan and Brian Duffy, Bailey captured and helped create the 'Swinging London' of the 1960s: a culture of fashion and celebrity chic. The three photographers socialized with actors, musicians and royalty, and found themselves elevated to celebrity status. Together, they were the first real celebrity photographers, named by Norman Parkinson "the Black Trinity".
Bailey's ascent at Vogue was meteoric. Within months he was shooting covers, and, at the height of his productivity, he shot 800 pages of Vogue editorial in one year. Since 1966, Bailey has also directed several television commercials and documentaries.