Narses spent most of his life as a relatively unimportant eunuch in the place of the emperors in Constantinople, but when Justinian became emperor in 527, historical events conspired to make him famous. In 532, he played a key role in suppressing the Nika riots, along with Belisarius, the other great general of the time.
He was 74 years old in 552, when the ever-suspicious Justinian recalled Belisarius from his campaign against the Ostrogoths in Italy and replaced him with Narses. Despite his age, he proved to be just as energetic and skilled as his predecessor. He launched yet another campaign against the Ostrogoths, finally defeating their formidable King Baduila at the Battle of Taginae. Two years later, he drove the Franks and Alamanni, who had come to help the Ostrogoths, back over the Alps. Eventually, the surviving Ostrogoths surrendered to him, and Italy was restored to the empire.
Narses remained in Italy as its prefect (governor), but his administration was unpopular. After Justinian's death, his son Justin II removed him as prefect and demanded he return to Constantinople. Narses relinquished his post, but refused to leave Italy, instead retiring to a villa near Naples.
The last years of his life are somewhat clouded in suspicion. Many sources at the time say Narses secretly encouraged the invasion of Italy by the Lombards in 568, in revenge for Justin II's taking away his position. Still, Narses, then 90 years old, offered his services to the emperor once more. He was turned down. By the time Narses died, more than half of Italy had fallen into Lombard hands.