One night in 1118, he interrupted the College of Cardinals in Santa Maria in Pallara sul Palatino, near his castle, and arrested the newly elected Pope Gelasius II and some of his followers.
In Spring 1121, Pope Callistus II destroyed the Frangipani fortress in Rome and prohibited its reconstruction.
In 1124, in alliance with Cardinal Aimerico of Santa Maria Nova, the papal chancellor and leader of the French reform party, Cencio forced the election of Honorius II.
In 1128, Cencio and Aimerico together travelled to the court of Count Roger II of Sicily to invest him with the Duchy of Apulia from the pope.
Cencio was exiled from the city for the next three years until his return on 4 June 1133 to be present at Lothair's imperial coronation.