He was the leader of Combatant Clergy Association and Chairman of the Assembly of Experts and also founder and president of Imam Sadiq University.

[3] Mahdavi Kani refused to join Islamic Republican Party in 1979, because he believed clerics should remain non-partisan.

[5] He was appointed chief of the Central Provisional Komiteh for the Islamic Revolution that was a body in charge of trials and executions of the civil and military officials of the Pahlavi era.

[2] He was elected as chairman of the Assembly of Experts on 8 March 2011 after Ali Akbar Hashemi Rafsanjani resigned from office.

[8][9] Mahdavi Kani was hospitalized for a stroke on Ruhollah Khomeini's death anniversary, which brought him to coma on 4 June 2014.

Hours after Mahdavi Kani's death, his office announced that his state funeral will be held on 23 October and his body will be buried at Shah-Abdol-Azim shrine.