Fleischer was born in Vienna, Austria; in his childhood his family immigrated to the USA in 1887 and settled in New York City.
Fleischer had the idea of using frames of a live action film as the basis for drawing animation, his patent for the rotoscope was granted in 1917, although Max and Dave Fleischer made their first cartoon using the device in 1915.
In 1919 he established Fleischer Studios for producing animated cartoons and short subjects. His brothers Dave Fleischer and Richard Fleischer also worked there.
Fleischer invented the rotograph, the first technique for adding animated characters to live backgrounds. Extensive use of this technique was made in Fleischer's Out of the Inkwell series, one of the highlights being a boxing match between the cartoon Koko the Clown and a live kitten.
Fleischer was also responsible for the "follow the bouncing ball" sing along cartoons.
Fleischer produced the first sound animated cartoons in 1924 using the Lee DeForest sound-on-film synchronization process (years before Steamboat Willie, which the Disney Corporation likes to imply was the first sound cartoon).
Fleischer's studio was bought out by Paramount Pictures in 1942.
Fleischer died in Woodland Hills, California