Having long wanted to call himself king, Stefan set about procuring a royal crown from the papacy. It is not clear what Stefan promised in regard to the status of the Catholic Church, which had numerous adherents in the western and coastal parts of his realm, but a papal legate finally arrived in 1217.

Since the Roman Catholic Church already had ambitions to spread its influence to Southeastern Europe as well, Stefan used these circumstances to eventually obtain the recognition of kingship from the Pope. Stefan the First-Crowned is crowned the King of the Serbs by Pope Honorius III establishing the Second Serbian Realm. The influence of the Catholic Church in Serbia did not last long but angered Serbian clergy. Many opposed Stefan's coronation, with Sava protesting by leaving Serbia and returning to Mount Athos. 

Stefan Nemanjić declared his independence from Byzantium and was crowned as king, adopting the title: "Crowned King and Autocrat of all Serbian and coastal lands".