After dropping out of college, Hannah briefly worked as an architectural engineer and helped build the Pantachis Theatre in Hollywood. He lost his job during the Great Depression and got a job in a car wash shop. His sister's boyfriend encouraged him to apply for a job at Pacific Title Art Company, which mainly makes movie title cards. During her work in this company, Hannah's painting talent became very obvious, so she joined Harman and Eisen Animation Studio at 1930. The famous works of this studio include Le Yitong and Merry Melody. Although lacking formal training, Hannah soon became the head of the company's traditional animation department. Besides painting, Hannah writes songs. In the first few years of this work, the studio had a cooperative relationship with Leon Schlesinger of Pacific Title Art Company. Schlesinger distributed the studio's work through Warner Bros. at 1933. Hugh Harman and Rudolf Ising chose to end their cooperation with Schlesinger and started making cartoons for MGM independently. Hannah was one of the employees who chose to follow them at that time.
1936, Hannah got the first chance to direct an animated film. To Spring is one of the animated short films of Happy Harmony by Harman and Eisen. A year later, MGM decided to set up a new animation production department and hand over the animation production work to the company instead of continuing to cooperate with Harman and Eisen. Hannah is the first employee of MGM's new animation department. From 1938 to 1939, he was the senior director of MGM's Captain and Children, which was adapted from the comic book of the same name. Due to the poor performance of this series, Hannah was downgraded to a story writer, and The Captain and the Children was cancelled. Hannah and joseph barbera are sitting opposite the desks of MGM, and they soon realize that each other and themselves will make good partners. 1939, they consolidated this partnership that will last for more than 60 years. Hannah and Babela collaborated with animation director tex avery, who produced daffy duck and bugs bunny for Warner Bros. and directed the Droubi series for MGM.