[3] Berenice's father was Ptolemy IX Soter, who became king of Egypt in 116 BC, with his mother Cleopatra III as his co-regent and the dominant force in government.

In 107 BC, Cleopatra whipped up the Alexandrian mob against Ptolemy IX, causing him to flee to Cyprus, abandoning Berenice and her brothers in Alexandria in the process.

[12][13][14] Berenice returned to Egypt at some point after Ptolemy X's death and before 81 BC, but the exact date is not known.

Ptolemy died shortly thereafter, probably in December of the same year, leaving Berenice alone on the throne.

At this point she was reincorporated into the dynastic cult as the Thea Philopator (Father-loving God), a clear reference to her inheritance of power from her father.

[15] After a few months of sole rule, Berenice summoned her younger half-brother and former step-son, Ptolemy XI, from Rome to serve as co-regent.

According to Appian, this co-regency was established at the behest of the Roman dictator Sulla, who hoped that Ptolemy XI would serve as a pliant client king.

[17] Berenice's death angered the Alexandrians, and in response to her murder the people rioted on 22 April 80 BC.