Hilderic's reign is noteworthy for the kingdom's excellent relations with the Eastern Roman Empire.

Procopius writes that he was "a very particular friend and guest-friend of Justinian, who had not yet come to the throne", noting that Hilderic and Justinian exchanged large presents of money to each other.

Hilderic had allowed a new Catholic bishop to take office in the Vandal capital of Carthage, and many Vandals began to convert to Catholicism, to the alarm of the Vandal nobility.

By the time he assumed the crown, he was quite old, at least into his fifties and possibly over sixty.

For this reason, according to Procopius, he was uninterested in the military operations of the Vandals and left them to other family members, of whom Procopius singles out for mention his nephew Hoamer.

After seven years on the throne, Hilderic falls victim to a revolt led by his cousin twice removed, Gelimer, an Arian, who leads the people in a religious rebellion.

The staunchly anti-Roman Gelimer now becomes King of the Vandals and Alans, and restores Arianism as the official religion of the kingdom, greatly worsening relations between Constantinople and Carthage.

He imprisons Hilderic, along with Hoamer and his brother Euagees, but does not kill him.

Justinian protests Gelimer's actions, demanding that Gelimer return the kingdom to Hilderic.

Gelimer sends away the envoys who bring him this message, replying: “nothing is more desirable than that a monarch should mind his own business.” He blinds Hoamer and puts both Hilderic and Euagees under closer confinement, claiming that they had planned a coup against him.