From around 1200, Emeric was deeply involved in the affairs of the Balkan Peninsula.
On 11 October 1200, Pope Innocent urged him to take measures to liquidate the "heretics" in Bosnia.
Upon Emeric's request, the Pope refused to send a royal crown to Grand Prince Stephen of Serbia.
Emeric invaded Serbia in 1201 or 1202, and helped Stephen's brother Vukan seize the throne.
As a token of his suzerainty over Serbia, Emeric became the first Hungarian monarch to adopt the title of King of Serbia in 1202.
He was also the first king to use a royal seal depicting the so-called "Árpád stripes", which eventually became part of the coat of arms of Hungary.

In the summer of 1202, the Venetian doge Enrico Dandolo signed a treaty with the leaders of the Fourth Crusade, who agreed to help the Venetians recapture Zadar, a town in Dalmatia, which had accepted the Hungarian monarchs' suzerainty since 1186.
Even though Pope Innocent III forbade the crusaders to besiege Zadar, they seized the town on 24 November and gave it to the Venetians.
Although the Pope excommunicated the Venetians and the crusaders upon Emeric's demand, Zadar remained under Venetian rule.

In fear of a crusade by Emeric, Ban Kulin of Bosnia held a synod of the Church of Bosnia at Bilino Polje on 6 April 1203.
The synod acknowledged papal primacy and ordered the reform of the rites.
Kulin also acknowledged Emeric's suzerainty.
In a letter written in 1203, the Bulgarian tsar Kaloyan informed Pope Innocent that Emeric had occupied five districts in Bulgaria, and Kaloyan demanded the Pope's intervention.
From around 1200, Emeric was deeply involved in the affairs of the Balkan Peninsula. On 11 October 1200, Pope Innocent urged him to take measures to liquidate the "heretics" in Bosnia. Upon Emeric's request, the Pope refused to send a royal crown to Grand Prince Stephen of Serbia. Emeric invaded Serbia in 1201 or 1202, and helped Stephen's brother Vukan seize the throne. As a token of his suzerainty over Serbia, Emeric became the first Hungarian monarch to adopt the title of King of Serbia in 1202. He was also the first king to use a royal seal depicting the so-called "Árpád stripes", which eventually became part of the coat of arms of Hungary.
In the summer of 1202, the Venetian doge Enrico Dandolo signed a treaty with the leaders of the Fourth Crusade, who agreed to help the Venetians recapture Zadar, a town in Dalmatia, which had accepted the Hungarian monarchs' suzerainty since 1186. Even though Pope Innocent III forbade the crusaders to besiege Zadar, they seized the town on 24 November and gave it to the Venetians. Although the Pope excommunicated the Venetians and the crusaders upon Emeric's demand, Zadar remained under Venetian rule.
In fear of a crusade by Emeric, Ban Kulin of Bosnia held a synod of the Church of Bosnia at Bilino Polje on 6 April 1203. The synod acknowledged papal primacy and ordered the reform of the rites. Kulin also acknowledged Emeric's suzerainty. In a letter written in 1203, the Bulgarian tsar Kaloyan informed Pope Innocent that Emeric had occupied five districts in Bulgaria, and Kaloyan demanded the Pope's intervention.
Emeric, King of Hungary