At the Council of Lodi in 1161, Frederick Barbarossa appointed him archbishop of Mainz to end a schism between Rudolf of Zähringen and Christian von Buch in that see.
After Victor's death in 1164, Rainald of Dassel, the archbishop of Cologne, chose as antipope Paschal III at Lucca.
He fled to France and then Rome in 1165 and his see was bestowed on Christian von Buch, though Alexander III still recognised him as legal archbishop.
When Christian died in 1183, Conrad could again assume his archiepiscopal responsibilities in that city, which, in 1160, had been deprived by the emperor of its charter for the murder of the archbishop Arnold of Selenhofen.
While Conrad was in the Holy Land acting as legate for Pope Celestine III, he intervened in the princely succession of Antioch.
On 6 January 1199, with papal permission, Conrad crowned Leo II, Lord of the Mountains, King of Armenia as a vassal of the Holy Roman Empire.