Sigismondo d' Este (September 1480 – August 9, 1524) was the youngest son of Ercole I d'Este, Duke of Ferrara, and Eleanor of Aragon, daughter of Ferdinand I of Naples.
After his father's death, the title passed to his brother Alfonso I d'Este.
Sigismund often accompanied the Duke on his travels in and out of the duchy.
When the conspiracy organized by Ferrante and Giulio was discovered, the trial against the two and other conspirators took place in the palace of Sigismund.
Alfonso and Ferrante contracted syphilis between 1496 and 1497, but while the brothers were able to recover Sigismund was unable to lead a normal life.