Pepi I was the son of Teti and a woman named Iput I, who is assumed by some to have been a daughter of Unas. He had several wives, the most notable being two sisters, Ankhenesmerire I and Ankhesenmerire II, daughters of a nobleman from Abydos, named Khui. Both marriages may have had political motivations, either by affiliating Khui to the royal family making Khui more influential, or vice versa, by affiliating a royal family on the decline, with Khui’s powerful clan.
Both successors of Pepi I were born from these marriages: Merenre I was the son of Ankhenespepi II and Pepi II was the son of Ankhenespepi I. It has, however, been suggested that Merenre I married Ankhenespepi I and that it was he, and not Pepi I, who was the father of Pepi II.
The 20 years accorded to Pepi I in the Turin King-list is too low and perhaps the result of a mistake of the composer or copyist of the king-list, or of a bad restoration by more recent scientists. The highest recorded year is the year after the 25th counting. If the counts occurred every 2 years, the year after the 25th counting would be the 50th year.
The internal policy of Pepi I was a continuation of his father's attempts to consolidate the power of the central government. This is demonstrated by the extensive building policy of this king. Monuments were erected in Bubastis, Abydos, Elephantine and Dendara. In Dendara, his memory would be preserved by a now lost statue of Pepi I adoring Hathor, as shown in a few reliefs in the temple from the Greek-Roman era.
During his reign, there were the almost traditional expeditions to the Sinai and into Nubia. He also organised some expeditions to the Wadi Hammamat. The commercial relationship with the Near East was endangered by an invasion of a nomadic people into Palestine.
His funerary complex, called Men-nefer, was built at Saqqara South, a few kilometres to the South of his father's. It was built at some distance from the temple of Ptah of Memphis. Its name would be transferred to this temple from the 18th Dynasty on, and from there on would be applied to the entire city known now by the Greek version of its name, Memphis.