The able and intelligent young man received a good education, and was recommended by Bishop Volkold of Meissen to the service of Emperor Otto the Great.

Upon the emperor's death, Willigis as Primas Germaniae, on Christmas 983 crowned his three-year-old son Otto III Rex Romanorum at Aachen.

Together with Otto III he pushed the election of Pope Gregory V against the resistance of the Roman nobility led by Crescentius the Younger and was present at the consecration and at the synod convened a few days later.

The immediate monastery established in 852 was originally situated at Brunshausen in the Diocese of Hildesheim, but was transferred to nearby Gandersheim within the territorial limits of the Archdiocese of Mainz.

Upon the Emperor's early death, Archbishop Willigis on 7 June 1002 crowned the Duke of Bavaria Henry IV as King of the Romans at Mainz, after the assassination of his rival Margrave Eckard I of Meissen.

Willigis presided at the 1007 synod at Frankfurt am Main, where thirty-five bishops signed the bull of Pope John XVIII for the erection of the Diocese of Bamberg.

In Mainz he initiated the construction of the cathedral and consecrated it on 29 August 1009, dedicating it in honor of St. Martin of Tours, but on the same day, disastrously, it was destroyed by fire.