Saint Peter, King of Bulgaria, was the son of the formidable Bulgarian prince Simeon. He was renowned for his deep Christian piety and frequently sought the prayers, spiritual counsel, and guidance of Saint John of Rila (August 18; October 19).

King Peter concluded a peace treaty with Byzantium on terms favorable to Bulgaria. Under his reign, the Patriarch of Constantinople formally recognized the autonomy of the Bulgarian Church and affirmed the establishment of a Patriarchal throne in Bulgaria, a development of lasting benefit to the Bulgarian Church.

Saint Peter also worked diligently to eradicate the Bogomil heresy within his realm. He reposed in the year 967, at the age of fifty-six.