Born in Andria, in the South Italian Kingdom of Sicily, his mother died shortly after giving birth to him and he succeeded her as monarch of the Crusader state of Jerusalem.

Prince-Archbishop Siegfried III of Mainz, in his capacity as German archchancellor, acted as regent for the minor until 1242, when Frederick chose Landgrave Henry Raspe of Thuringia, and King Wenceslaus I of Bohemia to assume this function.

When Frederick II died in 1250, he passed Sicily and Germany, as well as the title of King of Jerusalem, to Conrad, but the struggle with the pope continued.

After reverses in Germany in 1251, Conrad decided to invade Italy, hoping to regain the rich dominions of his father, and where his half-brother Manfred was acting as regent.

That same year Conrad issued constitutions during the hoftag in Foggia, which were based on the well-known examples from Norman and early Staufer times.

After the death of Frederick II, riots began in parts of the kingdom of Sicily and several cities attempted to escape the royal control, forcing Conrad to take military action in order to suppress the revolts.

Steadily, Conrad consolidated his position in the kingdom and the formidable centralized government fashioned by his father continued to function effectively.

Conrad’s son, Conradin, attempted to reclaim the kingdom of Sicily but was also defeated by Charles of Anjou at the Battle of Tagliocozzo and executed soon after.

Notably, many princes took this opportunity to gain more influence with their vast wealth and relative stability as opposed to the fractured monarchy which had proven to be somewhat unreliable.