David was a cast member for ABC's Fridays television series from 1980 to 1982. A couple of years later, he became a writer for NBC's Saturday Night Live from 1984 to 1985. His time with the show was not quite as successful as he would have liked, though. Through the entire season as writer, David only got one sketch included in the show, and it was the last sketch of the night (where the weaker sketches are usually scheduled).
In 1989, David teamed up with comedian Jerry Seinfeld to create The Seinfeld Chronicles for NBC. The show was later retitled simply Seinfeld and became one of the most successful shows in television history. David appeared on the show many times as minor characters, including the voice of "George Costanza"'s boss, George Steinbrenner.
David was the primary inspiration for the character of "George Constanza" on Seinfeld.