When Oswald the Lucky Rabbit retired in 1938, following a nine-year run, Walter Lantz's studio went for months without recurring characters. It wasn't until late 1939, when Lantz had a trip to a zoo. There, the main attraction of the place was a young panda which Lantz drew pictures of. He would then use his drawings to construct a new character.
Andy's first cartoon was the aptly titled Life Begins for Andy Panda in 1939. (This was obvious wordplay on the perky titles of the popular Andy Hardy movies of that era. Ironically, a later Andy Hardy film was actually titled Life Begins for Andy Hardy.)