Florey worked as assistant director to Josef von Sternberg, Frank Borzage and Victor Fleming before making his feature directing debut in 1926. He turned out more than 50 movies over the next 23 years, ranging from the first Marx Brothers vehicle, "The Cocoanuts" (1929), to skillful low-budget crime programmers like "The Crooked Way" (1949). For many historians some of Florey's finest work is to be found in these lower-budget programmers and B films; he hit a peak at Paramount in the late 30s with films including "Hollywood Boulevard" (1936), "King of Gamblers" (1937) and "Dangerous to Know" (1938), all distinguished by their fast pace, cynical tone and striking use of moody, semi-expressionistic camera angles and lighting effects. Other notable films include the experimental short "Life and Death of 9413, A Hollywood Extra" (1927) and the creepy horror classic "The Beast with Five Fingers" (1946).
Florey was one of the first seasoned feature directors to turn to television in the 1950s, working in the new medium for over a decade.
He also wrote a number of books including "Pola Negri", "Charlie Chaplin" (both 1927), "Hollywood d'hier et d'aujord'hui" (1948), "La Lanterne magique" (1966) and "Hollywood annee zero" (1972).