Glycerius held the rank of Count of the Domestics at the Imperial court in Ravenna when he was raised to the Imperial purple by the western empire's new Magister militum (or Master of Soldiers), the Burgundian Gundobad[?], on or around March 3, 473. As a puppet of Gundobad who had succeeded the legitmately chosen emperor Anthemius, who had been murdered, he received no recognition from the eastern Roman court of Emperor Leo I.
Glycerius may have delayed the final end of the Western Empire for a few years. During his brief reign, Italy was threatened by both the Visigoths, living in southern Gaul and Spain at the time, and the Ostrogoths, living in Dalmatia. When the Ostrogoths moved into Gaul in 473, Glycerius sent Roman troops to the area, preventing the armies of the two branches of Goths from joining forces against Rome.
However successful he might have been, however, Leo was unwilling to tolerate his presence on the western throne, and appointed his relative Julius Nepos to that position. Nepos, with a powerful force given him by Leo, sailed from Dalmatia to the port city of Ostia, near Rome, in June 474. For whatever reason, Glycerius was there instead of at the capital of Ravenna, and he surrendered forthwith to Nepos.
Perhaps as a reward for his cooperation, Nepos granted the deposed emperor with the bisphoric of Salona[?], in Nepos' homeland of Dalmatia. Ironically, the two men crossed paths again only two years later, when Nepos was deposed by his own master of soldiers and forced to flee to Dalmatia, where he reigned as emperor-in-exile until 480.
A contemporary account by the historian Malchus[?] states that Glycerius was involved in a plot that resulted in Nepos' murder in either April or May of 480, most likely with the cooperation of Odoacer, the barbarian King of Italy. Another account states that after Nepos' death, Glycerius was appointed by Odoacer to be bishop of Mediolanum (modern Milan), then as now one of the largest cities in Europe. However, the surviving historical evidence to confirm either account is meagre, and even the date of Glycerius' death is unknown.