Serbian ultra-nationalist Vojislav Seselj has been found not guilty of war crimes and crimes against humanity over the Balkan wars in the 1990s.
The UN war crimes court at The Hague (ICTY) said he bore no individual responsibility for the crimes.
Mr Seselj had denied all the charges.
He was allowed to go to Belgrade in 2014 after being diagnosed with cancer. He was not present in the courtroom – he even refused the tribunal's offer to follow the verdict by videolink.
He has been taking part in anti-government rallies ahead of Serbian parliamentary elections later this month.
“With this acquittal on all the nine counts of the indictment, the arrest warrant issued by the Appeals Chamber is rendered moot,” said presiding judge Jean-Claude Antonetti.
“Vojislav Seselj is now a free man.”
Mr Seselj was a close ally of late Serbian President Slobodan Milosevic. He served as Serbian deputy prime minister from 1998 to 2000.
He surrendered to the ICTY voluntarily in 2003. When the court sought to appoint a defence lawyer against his wishes, he went on hunger strike.
The indictment charged him with three counts of crimes against humanity and six of war crimes for inciting ethnic cleansing in Croatia, Bosnia and the Serbian province of Vojvodina in the period August 1991-September 1993.
When the trial finally opened in 2007, prosecutors argued he was criminally responsible for the murder, torture and deportation of non-Serbs as part of his project to create a “Greater Serbia”.
They accused him of raising an army of volunteers who had committed “unspeakable crimes”.
In long outbursts, Mr Seselj berated the tribunal, challenged its legitimacy – and regretted the fact that it could not pass a death sentence on him.
Vojislav Seselj charges
-Deportation or forcible transfer of tens of thousands of Croat, Muslim and other non-Serb civilians in Bosnia-Herzegovina, Croatia and Serbia
-Murder and deliberate destruction of homes, other public and private property, cultural institutions, historic monuments and sacred sites
-Torture, beating, robbery, sexual assaults, and perpetuation of inhumane living conditions against Croat, Muslim and other non-Serb civilians by Serb soldiers during capture and in the detention facilities;
-Direct and public denigration through “hate speech” of the Croat, Muslim and other non-Serb populations
Days before the verdict, he said he would not go to The Hague voluntarily, adding: “If the government extradites me, then I will serve my time.”
But he insisted in an interview with the Russian TV network RT: “I don't regret a single day in the fight against the anti-Serbian court.”
In 2014, the court decided to release him for treatment on humanitarian grounds, with Serbia guaranteeing he would be returned for the verdict.
Serbian doctors said at the time that he was suffering from cancer of the colon which had spread to his liver.
In the event, Mr Seselj refused to return to The Hague and ICTY judges agrees he could stay in Belgrade for the verdict.
Since its establishment, the ICTY has indicted 161 persons.
Last week, it convicted former Bosnian Serb leader Radovan Karadzic of genocide and war crimes in the war in Bosnia. He was sentenced to 40 years in jail.
Gen Ratko Mladic, who commanded Bosnian Serb forces, is also awaiting his verdict at The Hague, BBC reports.