His trial, followed by the three years of appeals, was the most important in the 23-year history of the United Nations tribunal, and was widely seen as a test of whether the modern international criminal justice system could impose accountability on wartime leaders.

The proceedings thoroughly investigated the bloodiest conflict in Europe since World War II, which tore apart Yugoslavia, ravaged several of the smaller nations that emerged from it and left more than 100,000 people dead. Among the Balkan combatants — Serbia, Bosnia, Kosovo and Croatia — millions of people were displaced, many of them forced from their homes in campaigns of ethnic cleansing.

The tribunal has tried many figures for crimes in the wars that broke up Yugoslavia. Mr. Karadzic and Gen. Ratko Mladic, the former Bosnian Serb commander, are the most senior figures to be convicted. Slobodan Milosevic, the Serbian president whose extreme nationalism instigated and enabled the bloody conflict, died in 2006 in his cell in The Hague before the end of his trial.

The genocide conviction of Mr. Karadzic dealt with the Srebrenica massacre, when 8,000 Bosnians, mostly men and boys, were rounded up and systematically murdered.

Members of the Mothers of Srebrenica, an organization of survivors of Srebrenica and a nearby village, Zepa, were present at The Hague on Wednesday.

At the Potocari Memorial Center, close to the scene of the Srebrenica massacre, local residents, including relatives of the victims, gathered to watch the tribunal’s result through an online video stream.

The appeals were little covered by the news media in Serbia, where The Hague’s tribunal is widely viewed as anti-Serb and many Serbs see Mr. Karadzic as a hero.