In 969 he was appointed imperial chaplain in Italy, and in 972 he was nominated by Otto I, Holy Roman Emperor as bishop of Liège, a suffragan of the Archbishop of Cologne.

After receiving secular power from Otto II, Notker transformed the episcopal city into the capital of an ecclesiastical principality in the Holy Roman Empire.

By procuring the services of Leo the Calabrian and thus making possible the study of Greek, Notker gave notable extension to the Liège curriculum.

Among Notker's pupils, who extended the influence of the Liège schools to ever wider circles, may be mentioned Hubald, Wazo of Liège, Franco, who also taught at Liége, Gunther of Salzburg, Ruthard of Mainz and Erluin of Cambrai, Heimo of Verdun, Hesselo of Toul, Heriger of Lobbes, Adelmann (who later studied under Fulbert at Chartres), Gozechin who taught at Mainz and Adalbald of Utrecht.

Johannes Fried considers Notker, rather than John Canaparius, the author of the Vita sancti Adalberti episcopi Pragensis, a life of Adalbert of Prague written around 1000, which contains the first recorded mention of Danzig/Gdansk, as urbs Gyddanyzc.