Born in Hornburg, Lower Saxony, Germany, he was the son of Count Konrad of Morsleben and Hornburg and his wife Amulrad. Before he was elected Pope, Suidger had been bishop of Bamberg from 1040 to 1046.
King (later Emperor) Henry III (1039–56) nominated Suidger for the Papacy upon the abdication of Pope Gregory VI (1045–46) which took place on December 1046 following the Council of Sutri. Immediately after his election, Clement II crowned Henry III as Holy Roman Emperor. All this was met with criticism from church reformers, although Clement II's short pontificate, starting with the Roman synod of 1047, initiated an improvement on the state of things in the Roman Catholic Church, particularly through enacting decrees against simony.
Clement II died in October 1047, and was interred at Bamberg, which he had loved dearly. A recent toxicologic examination of his remains confirmed centuries old rumors that the Pope had been poisoned with lead sugar. It is, however, not clear whether he was assassinated or not, as lead sugar in those times was often used as a cure for venereal diseases. Clement II's tomb in the western choir of the Bamberg Cathedral is the only tomb of a Pope north of the Alps.