Allen was born Allan Stewart Konigsberg in the Brooklyn borough of New York City, New York. He and his sister, Letty (b. 1943), were raised in Midwood, Brooklyn. He is the son of Nettie (nee Cherry; November 8, 1906 - January 27, 2002), a bookkeeper at her family's delicatessen, and Martin Konigsberg (December 25, 1900 - January 8, 2001), a jewelry engraver and waiter. His family was Jewish, and his grandparents immigrated to the US from Russia and Austria and spoke Yiddish, Hebrew, and German.

In 1966, Allen wrote the play Don't Drink the Water. The play starred Lou Jacobi, Kay Medford, Anita Gillette and Allen's future movie co-star Tony Roberts. A film adaptation of the play, directed by Howard Morris, was released in 1969, starring Jackie Gleason. Because he was not particularly happy with the 1969 film version of his play, in 1994, Allen directed and starred in a second version for television, with Michael J. Fox and Mayim Bialik.  The next play Allen wrote for Broadway was Play It Again, Sam, in which he also starred. The play opened on February 12, 1969, and ran for 453 performances. It featured Diane Keaton and Roberts. The play was significant to Keaton's budding career, and she has stated she was in "awe" of Allen even before auditioning for her role, which was the first time she met him. During an interview in 2013, Keaton stated that she "fell in love with him right away," adding, "I wanted to be his girlfriend so I did something about it." After co-starring alongside Allen in the subsequent film version of Play It Again, Sam, she would later co-star in Sleeper, Love and Death, Interiors, Manhattan and Annie Hall. "He showed me the ropes and I followed his lead. He is the most disciplined person I know. He works very hard," Keaton has stated. "I find the same thing sexy in a man now as I always have: humor. I love it when they are funny. It's to die for."  For its March 21, 1969, issue, Life featured Allen on its cover. In 1981, his play The Floating Light Bulb premiered on Broadway and ran for 65 performances. While receiving mixed reviews, it gave an autobiographical insight into Allen's childhood, specifically his fascination with magic tricks. He has written several one-act plays, including Riverside Drive and Old Saybrook exploring well-known Allen themes.  On October 20, 2011, Allen's one-act play Honeymoon Motel opened as part of a larger piece entitled Relatively Speaking on Broadway, with two other one-act plays, one by Ethan Coen and one by Elaine May.

What else did Allen participate in?
Broadway, with two other one-act plays, one by Ethan Coen and one by Elaine May.