Reitherman began working for Disney in 1934, along with future Disney legends Ward Kimball and Milt Kahl. The three worked together on a number of classic Disney shorts, including The Band Concert, Music Land, and Elmer Elephant and in all, Reitherman worked on various Disney feature films produced from 1937 to 1981, including Snow White and the Seven Dwarfs (Slave in the Magic Mirror) to The Fox and the Hound (co-producer).

He did the climatic dinosaur fight in Igor Stravinsky's The Rite of Spring in Fantasia, the Headless Horseman chase in "The Legend of Sleepy Hollow" section in The Adventures of Ichabod and Mr. Toad, the Crocodile in Peter Pan, and Maleficent as a dragon in Sleeping Beauty (the former three he animated and the latter he directed). Beginning with 1961's One Hundred and One Dalmatians, "Woolie", as he was called by friends, served as Disney's chief animation director.