Zeno was from Rosoumblada in the province in south-eastern Asia Minor known as Isauria.
The emperor Leo called him to Constantinople as the leader of a force of Isaurians in order to counter the ever-growing German influence over the empire.
In AD 467-8 Zeno was given the powerful position of 'Master of Soldiers' in Thrace to repel an assault by the Huns under the son of Attila, Denzig (Densegich).
Though Aspar, the powerful German 'Master of Soldiers' of the eastern empire, well understood Zeno as an ambitious new opponent and sought to see him out of the way. An assassination attempt was made by a group of soldiers at his behest, but Zeno managed to escape to Serdica (Sofia) in advance.
In AD 469 he held the consulship. Thereafter he was granted the post of 'Master of Soldiers' of the eastern provinces. In this role he set out to deal with brigandry and banditry of the Isaurian warlord Indacus.
But Zeno's ambitious suffered a setback as Leo elevated Aspar's son Patricius to the rank of Caesar and betrothed him to his daughter Leontia. Further still Aspar, through his elder son Ardaburius, was trying to win the support of Zeno's power base, the Isaurian guard, in order to regain supremacy over his rival.
Zeno moved back to Chalcedon from where he could influence matters in Constantinople.
In October AD 473 Leo elevated his five year-old grandson, who was the son of Zeno and Aelia Ariadne, to be co-emperor Leo II.
On 18 January AD 474 Leo died and Leo II was sole emperor, with Zeno as regent of the eastern empire. But already on 9 February Zeno was appointed co-Augustus by the senate.
Before the year AD 474 was over Leo II was dead. There were rumours that Zeno had killed his own son to have the throne for himself.
On his accession Zeno enjoyed a good relationship with the west. For the current western emperor, Julius Nepos, was related by marriage to Zeno's wife.
But just as Geiseric had at first taken offence, so too did the Ostrogothic chief Theodoric Strabo seize the opportunity of Aspar's death to renew hostilities with the eastern empire. After early successes, he though eventually was brought to a halt by the Isaurian general Illus.
Though Illus himself soon was the cause of trouble to Zeno, as he became involved in a conspiracy against the emperor at Constantinople. The conspiracy was a far reaching one, involving even Zeno's mother-in-law and widow of Leo, Aelia Verina.
Zeno though received a warning that his life was in danger and fled to his homeland of Isauria.
Though Basiliscus' reign was not to last for long. So unpopular was his rule, that he soon lost much of the support which had carried him to power.
With Illus' support Zeno now marched out of Isauria towards Constantinople. So unpopular was Basiliscus by then that an army which was sent against them, under command of Armatus, the empress' lover, on purposely avoided them, to allow them an unopposed passage toward the capital.
There was simply no resistance when Zeno re-entered his capital in August AD 476.
One of his first roles as re-instated emperor was to oversee the formal end of the western empire, traditionally referred to as 'the fall of Rome'.
Zeno recognized Odoacer as a patrician (patricius) and ruler of Italy, though insisted on Julius Nepos continuing, though in exile, as emperor of the west.