Ladislav Pejačević was the eldest son of Ferdinand Karlo Rajner /Ferdinand Charles Rainer/ (1800–1878) whose mother was Hungarian Countess Mária Eleonóra née Erdődy /monyorókeréki and monoszlói branch/ (1769—1840).

On 25 November 1852 he married the baroness Gabrijela /Gabrielle/ Döry de Jobaháza and they had three children: Marija, Teodor /Theodore/ and Mario Marko Aleksandar.

Pejačević entered politics as a young man, having become an assessor at the Croatian Parliament seat in Zagreb from 1844 until 1848.

As the reincorporation of the Croatian and Slavonian Frontiers into Croatian-Slavonian Crown land was proclaimed on 15 July 1881, Pejačević was given the task to perform it.

Ramberg was then succeeded by Károly Khuen-Héderváry, a Hungarian political hardliner, whose reign was marked by strong Hungarization.