Buoso Donati, wealthy but miserly Florentine, has taken his last breath. The deathbed is surrounded by grasping relatives who vie with each other in expressions of grief until they learn that old Buoso may have left his money to the monks. If the will has not yet been filed, however, there is still hope. After a frantic search, Rinuccio finds the will and extracts a promise from his aunt that she will consent to his marriage with Lauretta, daughter of Gianni Schicchi. Zita grudgingly gives permission and Rinuccio sends the little boy, Gherardino, to fetch Schicchi before his aunt can change her mind.

The will is opened and the relatives’ worse suspicions are confirmed. Rinuccio suggests chat they apply to the clever Schicchi for help, but this suggestion is met with scorn. When Schicchi enters, he is at first puzzled by the now sincere expressions of sorrow he finds on all sides. When he learns of Buoso’s final prank, Zita, in a fury, invites him to leave, but Lauretta pleads with her father, and he consents to try to find a way of circumventing the will. After assuring himself that no one outside of the room has learned of Buoso’s death, he conceives a scheme and is about to put it into effect when a knock at the door announces the visit of Buoso’s physician. Imitating Buoso’s shaking voice, Schicchi persuades the near-sighted doctor to return later that evening. Then he explains his plan to the family: he will impersonate Buoso and dictate a new will to the notary.

The relatives all state their preferences for portions of the estate, but when they are through, the three most valuable items are left unclaimed: the mule, the house and the saw-mills at Signa. Simone tries to claim them but is deterred by the rest of the family. This argument is interrupted by the tolling of a funeral bell and everyone fears that word of Buoso’s death has reached the outside. Gherardo discovers that the bell is tolling because of the death of the servant of a local dignitary. The disposition of the three choice items is left to the good judgment of Schicchi. As the relatives prepare him for the impersonation, each tries to bribe him, and he agrees to all of their propositions. Before climbing into bed, Schicchi reminds the family that the penalty for falsifying a will is amputation of the right hand and exile from Florence.

The notary and witnesses arrive and Schicchi dictates in Buoso’s trembling voice, leaving the minor portions of the estate to the relatives as they had requested. However, he leaves the three choice items to “his dear friend, Gianni Schicchi.” The relatives threaten to rebel but they are reminded of the penalty of amputation. When the notary and witnesses leave, they vent their anger on Schicchi who orders chem out.

Lauretta and Rinuccio come in from the balcony, singing of their love and their forthcoming marriage. Schicchi, who wisely recognizes that the entire Donati fortune will be reunited with them, asks the audience to pardon his trickery.