Having progressed through the Holy Orders, Fr. Platon became a member of the [[Holy Synod]] in 1768, and in 1770, he was [[consecration of a bishop|consecrated]] [[Bishop]] of Tver. While being named Bishop of Tver, Bp. Platon remained in St Petersburg where he was named the religious instructor of the new grand duchess. In 1775, he was enthroned archbishop of Moscow, a position he held through the reigns of Catherine II, Paul, and Alexander I. As archbishop, Platon diligently promoted the religious, moral, intellectual, and material welfare of his archdiocese. In 1787, Abp. Platon was elevated to metropolitan of Moscow. He maintained his residence outside the city: at Trinity-St. Sergius [[monastery]] in the winter and at the Pererva monastery in the summer. He personally supervised the education of the seminarians at the monasteries that included three students who would succeed him as archbishop of Moscow.
Metr. Platon maintained a lenient policy toward the Old Believers, allowing them to establish a number of chapels in the city of Moscow, including at the Preobrazhenskoe cemetery. He formalized the arrangement, known as [[Edinoverie]], that Abp. Nikephoros of Slaviansk had introduced earlier that allowed Old Believer communities to join the Church of Russia while using their traditional rites. These communities became known as Old-Ritualists,
Even in his associations with the court, Metr. Platon maintained his firmness and independence, yet enjoyed close and cordial relations. He crowned Paul as emperor in 1797 and Alexander I in 1801. He reposed on [[November 11]], 1812, shortly after he evacuated Moscow before Napoleon entered Moscow.