Raised in a Jewish family[2] in Brooklyn, Leavitt began his television career in the 1970s writing episodes for the comedies Busting Loose, Happy Days, Laverne & Shirley, and The Bad News Bears (for which he garnered an NAACP award).
In the early 1980s, in addition to writing and producing The Jeffersons (for which he won a People's Choice Award and a second NAACP award), Leavitt co-wrote the pilot for Silver Spoons and co-created and executive produced the Jason Bateman sitcom It's Your Move.
In the late 1980s, Leavitt co-created Married... with Children, which, with its debut on the Fox network in 1987, broke many of the established rules and mores of television.
Its longevity over 11 seasons made Married... with Children the second-longest running sitcom on Fox, just behind The Simpsons.
Other achievements outside television include recognition by the State of California as Citizen Hero of the Year in 2001, and the equally notable accomplishment of out-eating wrestler King Kong Bundy in a cheesesteak sandwich-eating contest at Dominick's Kitchen while Bundy was guest-starring on Married... with Children.