As an animator, his ability to draw a character quickly, cleanly, and accurately earned him the position of senior model sheet artist, troubleshooter, and animation supervisor at the studio. He is responsible for the classic pose of Bugs Bunny (leaning against a tree chomping a carrot) that to this day remains Bugs’ main publicity image, originally designed for a department store window display in 1943.

His directorial talents resulted in two Academy Award nominated films and the creation of Foghorn Leghorn, Speedy Gonzales, the Tasmanian Devil, and a host of other personalities in the Warner Bros. lineup.

McKimson worked at the Warner Studio longer than any of his peers, starting his career as an animator in 1932 and serving as director from 1945 until the animation unit closed its doors for the last time in 1968. Aside from the films staffing the characters he created, he was most noted for his animated spoofs of popular television programs of the day — "The Honeymousers," “Stupor Duck," "Wild, Wild World," "The Mouse That Jack Built" (starring the actual voices of the Jack Benny Show cast), and numerous others featuring Bugs, Daffy, and Elmer as television performers.

Until his death in 1977, McKimson continued to work in animation, directing for the DePatie/Freleng studio (creators of the Pink Panther series) and producing animated television commercials. Though often overlooked amid the Joneses, Clampetts, and Frelengs, Robert McKimson remains as important as any member of the Warner Bros. Studio during its "Golden Age" of animation.