He ruled as Duke of Bavaria-Munich from 1460 to 1467, and then as Duke of Bavaria-Dachau until his death. Sigismund was a son of Albert III of Bavaria with Duchess Anna of Brunswick-Grubenhagen. In 1468 the foundation stone of the Frauenkirche in Munich was laid by Sigismund.
He also ordered to enlarge Blutenburg Castle, to construct its chapel and to build the church Saint Wolfgang in Pipping nearby.
The redesign of the ducal court Alter Hof was initiated by Sigismund as well, who was generally a patron of the revival of Gothic arts in Bavaria. Sigismund is buried in the Frauenkirche in Munich.