Puzo succumbed to heart failure at his Long Island, New York, home, his agent said.
The writer suffered a near-fatal heart attack in 1991, but recovered sufficiently to pen yet another gangster bestseller, The Last Don (1996). That novel also got the Hollywood treatment in the form of a top-rated TV miniseries in 1997.
Just last week, reports said Puzo, along with director Francis Ford Coppola, was in talks with Paramount Pictures about a proposed Godfather, Part IV. Actors Leonardo DiCaprio and Andy Garcia were said to be already "on board" for the project.
Puzo won a pair of Oscars for cowriting the screenplays of the first two Godfather movies with Coppola. The two men also collaborated on 1990's less-acclaimed The Godfather, Part III.
In a statement Friday, Coppola called Puzo a "wonderful man" and said he felt a "personal loss" at his friend's death.
The former government clerk was an in-demand screenwriter in the 1970s, coming into his own in late middle-age with scripts for blockbusters such as Earthquake (1974), Superman (1978) and Superman II (1980), among others.
Prolific to the end, Puzo had recently finished his latest novel, Omerta, due to be published in 2000.
It is the murderous, yet alluring Corleone family of The Godfather that is Puzo's enduring legacy. He penned the original novel for a $5,000 advance--not a bad rate considering his first two novels had stiffed. Puzo supposedly used his mother, Maria, as the model for the story's imposing Don Vito Corleone (played in mumbling fashion by Marlon Brando in the first movie; and, by Robert De Niro in the second).
The book was an instant hit--as the first film would become three years later, introducing ominous catchphrases "It's not personal...it's strictly business," "Make him an offer he can't refuse," and "Sleeps with the fishes," into the pop-culture lexicon.
Puzo was 49 when The Godfather was published, finally distinguishing an as-yet undistinguished career. He never looked back, going onto million-dollar paydays for novels (including 1978's Fools Die) and scripts (a $1 million fee for 1984's The Cotton Club).
Born October 15, 1920, in New York City, Puzo is survived by five children.