[1] Puzo was born in the Hell's Kitchen section of New York City to Italian immigrants from the Province of Avellino; his father was from Pietradefusi and his mother from Ariano Irpino.

[2] When Puzo was 12, his father, who worked as a trackman for the New York Central Railroad, was committed to the Pilgrim State Hospital for schizophrenia,[3] and his wife Maria was left to raise their seven children.

[4] Mario Puzo served in the United States Army Air Forces in Germany in World War II, and later graduated from the City College of New York.

Under the pen name Mario Cleri, Puzo wrote World War II adventure features for magazine True Action.

[14][15] Paramount's Robert Evans relates that, when they met in early 1968, he offered Puzo the $12,500 deal for the 60-page manuscript titled Mafia after the author confided in him that he urgently needed $10,000 to pay off gambling debts.

[19] In mid-1972, Puzo wrote the first draft of the script for the 1974 disaster film Earthquake, but he was unable to continue work because of his prior commitment to The Godfather Part II.

However, in a review originally published in the San Francisco Chronicle, Jules Siegel, who had worked closely with Puzo at Magazine Management Company, speculated that Omertà may have been completed by "some talentless hack".

[4] In April 2022, Paramount+ began streaming The Offer, a 10-episode dramatic mini-series telling a fictionalized story of the making of The Godfather, including Puzo's decision to write the first book in what came to be a series.