(1920-1997) Michael initially wants nothing to do with the Corleone's "family business," and enrolls at Furman University in order to escape it. After the United States' entry into World War II, he enlists in the Marines and fights in the Pacific Theatre. For his bravery, Michael is featured in Life magazine in 1944. Michael is discharged as a Captain to recover from wounds in 1945. He later re-enters Dartmouth College, where he meets his future wife, Kay Adams (Diane Keaton). When his father is nearly assassinated in 1945, he volunteers to murder the men responsible, Virgil "The Turk" Sollozzo (Al Lettieri) and Captain McCluskey (Sterling Hayden), a police captain who was acting as Sollozzo's bodyguard. After committing the murders, Michael flees to Sicily under the protection of Don Tommasino and stays in hiding for two years. While in Sicily, he marries a young woman named Apollonia (Simonetta Stefanelli), but she is killed by a car bomb intended for Michael.

While in Sicily, he learns that his older brother Sonny (James Caan) had been murdered, and he returns to New York in 1950. There, he reluctantly becomes involved in his family's criminal enterprises, taking over for his deceased brother as head of the family under Vito's supervision. He marries Kay a year later. Michael tries to buy out casino owner Moe Greene's stake in the casino, intending to move his family to Nevada. After his father's death in 1955, he becomes official Don of the Corleone crime family. Before his death, Vito had warned Michael that after he was gone, the head of the rival Barzini family would make an attempt on his life under the pretense of organizing a meeting in order to make peace between the two families. After his father's caporegime, Sal Tessio (Abe Vigoda), inadvertently reveals that he had conspired with Emilio Barzini against him, Michael arranges the murders of the leaders of the New York Mafia's other ruling families: Dons Emilio Barzini, Philip Tattaglia, Carmine Cuneo, and Victor Stracci. Also targeted are Greene, Tessio, and Carlo Rizzi (Gianni Russo), his brother-in-law, who beat his sister Connie (Talia Shire) and sold out Sonny.

Michael appears as a secondary character in Puzo's The Sicilian. During his two-year exile in Sicily, Michael is eager to return home to his family in New York, but is told by caporegime Peter Clemenza that his father wants him to escort Salvatore "Turi" Guiliano safely back to America with him. As he learns more about the reputation and exploits of the legendary Giuliano, Michael becomes extremely intrigued to meet him, but due to Guiliano's later death, is unable to do so, much to his distress.

Michael and Roth travel to Cuba under Fulgencio Batista in order to forge a partnership with the Cuban government, allowing them to be free to conduct their operations in Cuba without interference from the authorities. In the midst of the chaos of the revolution of 1959, Michael discovers that Fredo had betrayed him.

By the time of The Godfather Part III (the late 1970s) Michael has taken great steps to making the family legitimate; he is preparing to hand over his interests in gambling to the other Mafia families, setting up a charitable foundation, and is even being recognized by the Vatican for his good works. This new connection to the Church gives Michael the opportunity to purchase a controlling stake in the large property conglomerate, Immobiliare. He also begins to rekindle his relationship with Kay, as well as taking Sonny's illegitimate son, Vincent Mancini (Andy Garcia), under his wing. He finds himself pulled back into the underworld, however, when almost the entire Mafia Commission is wiped out by an assassin as Michael prepares to hand over his criminal interests. Vinnie responds to this new threat against the Family with brutal violence, publicly gunning down Michael's rival, Joey Zasa (Joe Mantegna), who was thought to have ordered the hit on Michael. Vinnie also begins a relationship with Michael's daughter, Mary (Sofia Coppola), a romance Michael strongly disapproves of.

At the end of the film, weary of the bloody, lonely life of a Don, he retires and makes his nephew the new head of the family, on condition that he end the relationship with Mary. Realising that powerful interests in Italian politics and business were working to prevent the family's takeover of Immobiliare, Michael, with Vinnie's assistance, once again prepares to move against his enemies. This wave of murders takes place as Michael watches his son Anthony perform in the opera Cavalleria Rusticana. That same night, however, Mary is inadvertently killed in an assassination attempt on her father. Devastated by this loss, Michael retires to Sicily, where he dies years later (1997) of a stroke, alone.