The work of photographers, Alfred Stieglitz and Ansel Adams inspired Ronis to begin exploring photography. After his father's death, in 1949, Ronis closed the studio and joined the photo agency, Rapho, with Ergy Landau, Brassaï, and Robert Doisneau.
Ronis became the first French photographer to work for LIFE Magazine. In 1953, Edward Steichen included Ronis, Henri Cartier-Bresson, Doisneau, Izis, and Brassaï in an exhibit at the Museum of Modern Art entitled Five French Photographers. In 1955, Ronis was included in the The Family of Man exhibit. The Venice Biennale awarded Ronis the Gold Medal in 1957. Ronis began teaching in the 1950s, and taught at the School of Fine Arts in Avignon, Aix-en-Provence and Saint Charles, Marseilles. In 1979 he was awarded the Grand Prix des Arts et Lettres for Photography by the Minister for Culture. Ronis won the Prix Nadar in 1981 for his photobook, Le fil du hasard.
Ronis' wife, Anne Marie was the subject of his well-known,  photo, Provencal Nude. The photo, showing Anne Marie washing at a basin with a water pitcher on the floor and an open window through which the viewer can see a garden, is noted for its ability to convey an easy feeling of provencal life. Late in her life, Ronis photographed Anne Marie suffering from Alzheimer's disease, sitting alone in a hospital yard. Anne Marie died in 1991.
Ronis continues to live and work in Paris, although he stopped photography in 2001, since he required a cane to walk and could not move around with his camera, and now works on books for the Taschen publishing company.