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. With Ankhenesmerire I he had a son, Pepi II. With Ankhenesmerire II, a sister of her name-sake, he had a son, Merenre I and a daughter, Neith. His marriage to these two sisters may have been a political move since they were the daughters of a nobleman from Abydos, named Khui.

The 20 years accorded to him 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 countings 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 not only by his marriage to two daughters of a nobleman from Abydos, but also 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 that shows him 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 of Memphis.