In 1974-1984 he was the Rector of the Leningrad Spiritual Academy and Seminary.
In 1971 he was appointed representative of the Moscow Patriarchate at the [[World Council of Churches]] and has been actively involved in the
[[ecumenical ]] activity of the Russian Orthodox Church since then. In 1978, Kirill was appointed Deputy Chairman, and in November 1989, Chairman of the External Church Relations Department of the Moscow Patriarchate and permanent member of the Holy Synod. He is known as active and efficient diplomat.
On 6th December, 2008, the day after the death of [[List of Metropolitans and Patriarchs of Moscow|Patriarch]] [[Patriarch Alexius II of Russia|Alexy II]] ([]-2008), the Holy Synod elected him ''Locum tenens'' of the Patriarchal throne.