Abbott crossed paths with Lou Costello in the early 1930s when Abbott was producing and performing in Minsky's Burlesque shows and Costello was a rising comic. They first worked together in stock burlesque in 1935 at the Eltinge Theatre on 42nd Street, after an illness sidelined Costello's regular partner.^[1] They formally teamed up in 1936, and performed together in burlesque, vaudeville, minstrel shows, and stage shows.

In 1938, they received national exposure as regulars on the Kate Smith Hour radio show, which led to roles in a Broadway musical, The Streets of Paris in 1939. In 1940, Universal signed the team for their first film, One Night in the Tropics. Despite having minor roles, Abbott and Costello stole the film with several classic routines, including an abbreviated version of "Who's On First?" Universal signed the team to a two-picture deal, and the first film, Buck Privates (1941), became a major hit and led to a long-term contract with the studio. It was directed by Arthur Lubin who later said "I don't think there has ever been a finer straight man in the business than Bud Abbott. Lou would go off the script - because he was that clever with lines - and Bud would bring him right back."

During World War II, Abbott and Costello were among the most popular and highest-paid stars in the world. Between 1940 and 1956 they made 36 films and earned a percentage of the profits on each. They were among the Top 10 box office stars from 1941 through 1951, and placed No. 1 in 1942. They also had their own radio program (The Abbott and Costello Show) throughout the 1940s, first on NBC from 1942 to 1947, and from 1947 to 1949 on ABC. During a 35-day tour in the summer of 1942, the team sold $85 million worth of War Bonds. In the 1950s, they introduced their comedy to live television on The Colgate Comedy Hour, and launched their own half-hour filmed series, The Abbott and Costello Show.