Bettger's theatrical debut was in Brother Rat at the Biltmore Theatre in New York City in 1936. His Broadway credits include Dance Night (1938), Summer Night (1939), The Flying Gerardos (1940–1941), The Moon Is Down (1942), All for All (1943), Oh, Brother! (1945), John Loves Mary (1947–1948), and Love Life (1948–1949).