He was born in Našice as the eldest son of Ladislav Pejačević, a Ban of Croatia (1880–1883).

His mother was the Hungarian baroness Gabrijela /Gabrielle/ Döry de Jobaháza.

At the beginning of the 20th century, he was faced with a new direction of Croatian policy marked by political alliance between Croats and Serbs in Austria-Hungary for mutual benefit.

A Croat-Serb Coalition was formed in 1905 and it governed the Croatian lands from 1906 until the dissolution of the Dual Monarchy in 1918.

He also took part as the Minister for Croatia, Slavonia and Dalmatia in the Hungarian Government from 1913 to 1916.