Arlen was born Hyman Arluck, in Buffalo, New York, the child of a Jewish cantor. He learned the piano as a youth and formed a band as a young man. He achieved some local success as a pianist and singer and moved to New York City in his early 20s. As this point, he changed his name to Harold Arlen.
In 1929, Arlen composed his first well-known song: Get Happy (with lyrics by Ted Koehler). Throughout the early and mid-1930s, Alren and Koehler wrote shows for the Cotton Club, a popular Harlem night club, as well as Broadway musicals and Hollywood films. Alren also continued to perform with some success.
Alren and Koehler wrote the following hit songs during the early and mid-1930s:
In the 1940s, Arlen teamed up with lyricist Johnny Mercer.