From 1929 to 1941, Mrkonjić Grad was part of the Vrbas Banovina of the Kingdom of Yugoslavia.

In World War II, the town became renowned by the first meeting of ZAVNOBiH on 25 November 1943, when Bosnia and Herzegovina was proclaimed as a common republic of Serbs, Croats and Muslims.

During the Bosnian War from 1992 to 1995, the town was within the territory controlled by ethnic Serbs.
The town is also known for the Mrkonjić Grad incident where the USAF lost one F-16 in June 1995.
The pilot of the jet, Scott O'Grady, was stranded in the area for six days before being rescued by US Marines.
In 8–12 October 1995, Mrkonjić Grad was in the hands of the Croatian Army (HV) and the Croatian Defence Council (HVO).

After the Dayton peace agreement the town was assigned to the entity of Republika Srpska.
In 1996, a mass grave containing the bodies of 181 Serbs—mostly civilians—was uncovered in Mrkonjić Grad.
Almost all were killed by Croat forces in late 1995.
From 1929 to 1941, Mrkonjić Grad was part of the Vrbas Banovina of the Kingdom of Yugoslavia.
In World War II, the town became renowned by the first meeting of ZAVNOBiH on 25 November 1943, when Bosnia and Herzegovina was proclaimed as a common republic of Serbs, Croats and Muslims.
During the Bosnian War from 1992 to 1995, the town was within the territory controlled by ethnic Serbs. The town is also known for the Mrkonjić Grad incident where the USAF lost one F-16 in June 1995. The pilot of the jet, Scott O'Grady, was stranded in the area for six days before being rescued by US Marines. In 8–12 October 1995, Mrkonjić Grad was in the hands of the Croatian Army (HV) and the Croatian Defence Council (HVO).
After the Dayton peace agreement the town was assigned to the entity of Republika Srpska. In 1996, a mass grave containing the bodies of 181 Serbs—mostly civilians—was uncovered in Mrkonjić Grad. Almost all were killed by Croat forces in late 1995.
Mrkonjić Grad