The 1261 papal election took place after the death of Pope Alexander IV on 25 May and chose Pope Urban IV as his successor. Since Pope Alexander had been resident in Viterbo since the first week of May 1261, the meeting of the cardinals to elect his successor took place in the Episcopal Palace at Viterbo, which was next to the Cathedral of S. Lorenzo. The actual date of the beginning of the Electoral Meeting is unknown. If the canon of Pope Boniface III were still in effect, then the Election could not begin until the third day after the Pope's burial.

Pope Urban IV, born Jacques Pantaléon, was the head of the Catholic Church and ruler of the Papal States from 29 August 1261 to his death. He was elected pope without being a cardinal; he was the first to be elected in such a way, and this would occur for only 3 more popes afterwards.