Adalbert of Saxony (8 May 1467 in Meissen – 1 May 1484 in Aschaffenburg) was administrator of the Archdiocese of Mainz as Adalbart III.
Adalbert was the son of Elector Ernest of Saxony and his wife Elisabeth of Bavaria-Munich.
In order to protect the Thuringian areas of the Archdiocese of Mainz around Erfurt and in the Eichsfeld area, archbishop Diether von Isenburg and the cathedral chapter of Mainz appointed Aldalbert, who was still a minor, in 1477 as Provisor of the city of Erfurt and High Bailiff of Rusteberg Castle in Rustenfelde in the Eichsfeld.
After Dieter died, Adalbert succeeded him as ruler of the Archbishopric of Mainz on 8 May 1482.
The archbishop's residence, Martinsburg Castle in Mainz, was completed during Adalbert's reign.