The eldest son of Osorkon I, sent to Thebes to become High Priest (thus stopping the son of Iuput - the previous High Priest - from inheriting his father's post).
During his period as High Priest, Shoshenq left four statues at Karnak, two of which simply name him as high priest and son of King Osorkon, a finer one also gives the titles of his mother ('Prophetess of Hathor Lady of Dendera and God's Mother Harsomtus, Maatkare, royal daughter of King [Psusennes]'). The fourth statue dedicated by Shoshenq to the Nile god has the inscription: 'Lord of the South and North, Leader ... who is leader of the great army of all Egypt, son of King Osorkon' followed by 'High Priest of Amenresonter (Shoshenq beloved of Amun)'.
Towards the end of the reign of Osorkon I, the aging king took his son away from Thebes and made him his co-regent. Shoshenq at this point was in his fifties and become co-regent - Shoshenq II. However, Shoshenq was not destined to rule alone, he died suddenly and was buried by his father at Tanis.