Priesthood. Ordained, April 6, 1624.
Episcopate. Elected bishop of Camerino, November 29, 1627. Consecrated, November 30, 1627, patriarchal Liberian basilica, Rome, by Cardinal Scipione Caffarelli-Borghese, assisted by Giovanni Battista Altieri, former bishop of Camerino, and by Giovanni Battista Lancelotti, bishop of Nola. Succeeded his brother Giambattista as bishop of that diocese. Governor of Loreto, December 10, 1633. President of Romagna, June 4, 1636. Governor of Marche, per modum provisionis, January 22, 1641 until October 7, 1641. In charge of the safety of Ravenna against the floods of the river Po. Named apostolic visitor of the entire Papal States, could not exercise the post because of the Castro war. He declined promotion to the cardinalate in favor of an older brother. Nuncio in Naples, December 25, 1644 until 1652. Charged by the Sacred College of Cardinals, during the vacancy of 1655, with the mission of pacifying Lombardy. Secretary of the S.C. of Bishops and Regulars, 1657-1667. Consultor of the Supreme S.C. of the Roman and Universal Inquisition in the pontificate of Pope Alexander VII. Resigned the government of the see, June 7, 1666. Prefect of the Cubiculi of His Holiness, January 24, 1667.
Cardinalate. Created cardinal priest in the consistory of November 29, 1669; never received the red hat and the title because Pope Clement IX died on December 9, 1669 and he was elected his successor. Participated in the conclave of 1669-1670 and was elected pope.
Papacy. Elected pope on April 29, 1670. He protested his election because of his advanced age, but accepted and took the name Clement X. Crowned, May 11, 1670, Rome, by Cardinal Francesco Maidalchini, protodeacon of S. Maria in Via Lata. Took possession of the patriarchal Lateran basilica, June 8, 1670.
Death. July 22, 1676. Exposed and buried in the patriarchal Vatican basilica.