Denoff was born to a Jewish family[1] in Brooklyn, New York, the son of Esther (Rothbard) and Harry Denoff, a salesman.
[2] With his long-time collaborator Bill Persky he wrote and created the television show That Girl starring Marlo Thomas.
[3][4] Their writing collaboration on episodes of The Dick Van Dyke Show resulted in some of the show's most popular episodes.
Denoff also wrote for the 1976 Danny Thomas situation comedy The Practice.
[3] Denoff died from complications of Alzheimer's disease at his home in the Brentwood section of Los Angeles, at the age of 83.