Mili spent his childhood in Romania, attending Gheorghe Lazăr National College in Bucharest, and migrating to the United States in 1923.

Over the years his assignments took him to the Riviera (Picasso); to Prades, France (Pau Casals in exile); to Israel (Adolf Eichmann in captivity); to Florence, Athens, Dublin, Berlin, Venice, Rome, and to Hollywood to photograph celebrities and artists, sports events, concerts, sculptures and architecture.

Working with Harold Eugene Edgerton of MIT, Gjon Mili was a pioneer in the use of stroboscopic instruments to capture a sequence of actions in one photograph.

Trained as an engineer and self-taught in photography, Gjon Mili was one of the first to use electronic flash and stroboscopic light to create photographs that had more than scientific interest.

In 1944, he directed the short film Jammin' the Blues,[2][3] which was made at Warner Bros., and features performances by Lester Young, Red Callender, Harry Edison, "Big" Sid Catlett, Illinois Jacquet, Barney Kessel, Jo Jones and Marie Bryant.