After succeeding his father, Osorkon II was faced with the competing rule of his cousin, King Harsiese A, who controlled both Thebes and the Western Oasis of Egypt.

His successor, Shoshenq III, lost the effective control of Middle and Upper Egypt that Osorkon II had achieved.

Osorkon II devoted considerable resources into his building projects by adding to the temple of Bastet at Bubastis,[2] which featured a substantial new hall decorated with scenes depicting his Sed festival and images of his queen, Karomama.

[6] The fact that this king's own grandson, Takelot F, served him as High Priest of Amun at Thebes–as the inscribed walls of Temple J prove – supports the hypothesis of a longer reign for Osorkon II.

Recently, it has been demonstrated that Nile Level Text 14 (dated to Year 29 of an Usimare Setepenamun) belongs to Osorkon II on palaeographical grounds.

While Osorkon II's precise reign length is unknown, some Egyptologists, such as Jürgen von Beckerath – in his 1997 book Chronology of the Egyptian Pharaohs[8] – and Aidan Dodson have suggested a range of between 38 and 39 years.

[13] The French excavator Pierre Montet discovered Osorkon II's plundered royal tomb at Tanis on February 27, 1939.

[17] While the tomb had been looted in antiquity, what jewellery that remained "was of such high quality that existing conceptions of the wealth of the northern Twenty-first and Twenty-second dynasties had to be revised.