Theodore (Fyodor) Ekaterinovsky was born into the family of a priest in the Saratov region of Russia in 1820. He was educated at the Saratov Seminary and later at the Moscow Theological Academy. On October 12, 1841, he was tonsured a monk and given the name Peter. He was ordained to the diaconate a week later and to the priesthood on July 30, 1844.
Following completion of his studies at the Academy, he was appointed to teach at the Irkutsk Seminary on December 12, 1844 and became its inspector (dean of students) on November 15, 1845. On October 6, 1852, he was elevated to the rank of archimandrite; three years later, on October 16, 1855, he became rector of the Irkutsk Seminary. On January 15, 1857, he was appointed rector of the Novoarkhangelsk Seminary on the island of Sitka in Alaska. On March 29, 1859, he was consecrated Bishop of Novoarkhangelsk (now Sitka), Vicar of the Kamchatka Diocese.
Continuing the work of St. Innocent, he established new church schools in Kodiak and Unalaska and expanded missionary activity as far as the Bering Strait. He was also among the first to seriously investigate the life and legacy of the Monk Herman of Spruce Island. He was transferred to the see of Yakutsk on November 9, 1866, while remaining an auxiliary bishop of the Kamchatka Diocese. Following a leave of absence from July 3 until October 13, 1867, he was appointed to the staff of the Holy Synod office in Moscow and administrator of the Holy Resurrection Monastery.
On April 4, 1869, he was assigned to be diocesan bishop of Ufa and Menzelinsk, and was transferred to the Diocese of Tomsk and Semipalatinsk on November 19, 1876. He was again granted a leave of absence on July 9, 1883 with residence at the Optina Pustyn Monastery in the Kaluga Diocese. On February 11, 1885, he was appointed to head the Zaikonospassky Monastery in Moscow. On July 10 of the same year, he was again assigned to the staff of the Moscow office of the Holy Synod and on August 9 of that year as administrator of the Novospassky Monastery in Moscow. He died on May 27, 1889.
Bishop Peter was a man of deep humility and monastic asceticism. He was a prolific writer on spirituality. Among his published works, which are currently being rediscovered and highly regarded in post-communist Russia, the most widely known are devoted to monasticism, missionary work, biblical commentary and various spiritually edifying topics. He left his writings and manuscripts to the Optina Pustyn Monastery. Bishop Peter labored tirelessly to disseminate spiritual and educational publications.