Karadzic faces charges on 11 counts of crimes against humanity, breaching the laws or customs of war and genocide for his role in the 1992-1995 Bosnian War.
Presiding Judge O-Gon Kwon is due to begin reading out the verdict at 13:00 GMT in a process expected to last around 2.5 hours.
Experts foresee the ICTY sentencing Karadzic to life in prison. Both the defense and prosecution, however, can appeal the verdict.
The Bosnian War erupted between Bosnian Muslims, Serbs and Croats when Bosnia and Herzegovina announced its secession from Yugoslavia in 1992.
Various estimates put the death toll in the conflict at around 100,000 people.
Karadzic is claimed to have overseen the massacre of an estimated 8,000 Muslim men and boys after Serbian forces overran the Bosnian town of Srebrenica in the waning days of the war in July 1995.