Josephus informs us that, after the murder of his father, Herod the Great sent him to Rome to the court of Tiberius, who conceived a great affection for him, and placed him near his son Drusus, who also befriended him. On the death of Drusus, Agrippa, who had been recklessly extravagant, was obliged to leave Rome. After a brief seclusion, Herod the Tetrarch, his uncle, who had married his sister Herodias, made him agoranomos (Overseer of Markets) of Tiberias, and gave him a large sum of money; but his uncle being unwilling to continue his support, Agrippa left Judea first for Antioch and afterwards returned to Rome, where he was welcomed by Tiberius and became the constant companion of Caligula, then a popular favourite. Agrippa being one day overheard by his freedman Eutyches, to express a wish for Tiberius' death and the advancement of Caligula, was betrayed to the emperor and cast into prison.
Following Tiberius' death and the ascension of his friend Caligula, he was made governor first of the territories of Batanaea and Trachonitis that his cousin Philip had held, then of the tetrarchy of Lysanias, with the title of king ("king Herod"). In AD 39 he returned to Rome and brought about the banishment of Herod Antipas, whose tetrarchy he then was granted.
On the assassination of Caligula (41) Agrippa helped by his advice to secure Claudius ascension as emperor, while he made a show of being in the interest of the senate. As a reward for his assisstance, Claudius gave him the government of Judea, while the kingdom of Chalcis in Lebanon was at his request given to his brother Herod. Thus Agrippa became one of the greatest princes of the east, the territory he possessed equalling in extent that held by his grandfather Herod the Great. He returned to Judea and governed it to the great satisfaction of the Jews. His zeal, private and public, for Judaism is recorded by Josephus and the rabbis; and the narrative of Acts 12 gives a typical example of it. About the time of the Passover in 44, James the Great, the son of Zebedee and brother of John the Apostle, was seized by his order and put to death. He proceeded also to lay hands on Peter and imprisoned him. After the Passover he went to Caesarea, where he had games performed in honour of Claudius, and the inhabitants of Tyre and Sidon waited on him to sue for peace.
According to the story in Acts, Agrippa, gorgeously arrayed, received them in the stadium, and addressed them from a throne, while the audience cried out that his was the voice of a god. But "the angel of the Lord smote him," and shortly afterwards he died "eaten of worms." The story in Acts differs slightly from that in Josephus, who describes how in the midst of his elation he saw an owl perched over his head. During his imprisonment by Tiberius a similar omen had been interpreted as portending his speedy release, with the warning that should he behold the same sight again he would die within five days. He was immediately smitten with violent pains, and after a few days died. Josephus omits the detail of his being "eaten of worms". A third account omits all the miraculous elements in the story and says that Agrippa was assassinated by the Romans, who objected to his growing power.