Glycerius was born in Dalmatia. Glycerius rose to the rank of "comes domesticorum" during the reign of Western Roman emperor Olybrius, who was a puppet emperor controlled first by the "magister militum" Ricimer, and then by Ricimer's nephew, the "Magister militum" Gundobad. After the death of Olybrius on 2 November 472, and an interregnum of nearly four months, Gundobad proclaimed Glycerius as Western Roman Emperor at Ravenna on either 3 or 5 March 473; the "Fasti vindobonenses" states that it was on the 5th, however the "Paschale campanum" asserts it was on the 3rd.