Pepi II came to the throne as a child, while his mother Ankhenespepi I was regent of the country. For a long time, it had been assumed that Pepi II’s father was Pepi I and that Merenre I was Pepi II’s half-brother. The possibility of a 7 to 11 year long reign for Merenre I would, in view of Pepi II’s young age when he became king, may mean that it was Merenre I and not Pepi I who was Pepi II’s father.
Pepi II had several wives, among them, his (half-)sisters Neith, Iput II, Ankhenespepi III, Ankhenespepi IV and his daughter Udjebten.
His successor, Merenre II, was probably the son Pepi II had with Neith, while with Ankhenespepi III he was the father of Neferkare III, a 7th/8th Dynasty king.
According to the Turin King-list, Pepi II ruled for over 90 years, which appears to be confirmed by Manetho, who recorded 94 years. This would make Pepi II the longest ruling king of Ancient Egypt. Some doubt has however been shed on this high number, and some researchers believe that it was the result of a miss-reading of 64.
The actual power in the beginning of his reign was held by his mother and her brother, Djau. An alabaster statue shows Ankhenespepi I with the young but regal Pepi II on her lap, somewhat reminiscent of Isis with the young Horus. Another statue, shows Pepi II as a naked child.
Pepi II's long reign is marked by a gradual decline of the central government. His predecessors' policy to try and consolidate the position of the king was starting to fail, and this would become more obvious after Pepi II's death. It is often believed that the cause of this was the long reign of Pepi II: the ageing king was no longer able to rule himself, which would have increased the power of his central administration and of the provincial governors. On the other hand, it must be noted that Pepi's funerary monument was built and decorated in a much poorer way than his predecessors', which may indicate a decline in welfare in general during his reign. This decline is likely to have been the result of the lower annual inundation of the Nile: with a lower annual inundation, harvests and crops were no longer abundant and agriculture, the backbone of Egyptian economy, began to decline.
Pepi II's foreign policy too is marked by some problems. In the beginning of his reign, a pygmy brought by the governor of Elephantine, could delight the young king. Later, several expedition leaders would find their deaths while campaigning in Nubia. The commercial relationship with Byblos appear to have continued, but many other commercial relationships with foreign countries were broken off.
Pepi II built his funerary complex in Saqqara South, near the monument of Shepseskaf of the 4th Dynasty, at a kilometre distance from his father’s and brother's. Three of his wives were buried in smaller pyramids next to his own.