Plavsic, 72, is the former president of the Bosnian Serb republic and the most senior politician from former Yugoslavia to be jailed by the Hague war crimes tribunal.
Smartly dressed in a blue blazer and wearing a large gold crucifix, the white-haired former biology professor looked tense as the judge, Richard May, rejected defence arguments that she should not receive a sentence of more than eight years as this would probably mean she would die in prison.
The British judge's sombre and detailed 40-minute statement carefully balanced the severity of her offences - mass killings, deportations and cruel and inhumane treatment - with the "very significant" mitigating factors of her guilty plea, remorse, and her subsequent contribution to peace.
The ruling in case IT-OO-39&40/1-S is a landmark in the 10-year history of the body set up to try the perpetrators of the crimes committed in the Balkan wars of the early 1990s.
"Undue leniency would be misplaced," Mr May said.
"No sentence which the trial chamber passes can fully reflect the horror of what occurred or the terrible impact on thousands of victims.
"These crimes did not happen to a nameless group but to individual men, women and children, who were mistreated, raped, tortured and killed."
There was immediate criticism from Balkan observers that 11 years was not long enough compared to other sentences passed by the tribunal.
Florence Hartman, a spokeswoman for the prosecution, said that the prosecutors had wanted a tougher sentence.
Sitting in the place that Slobodan Milosevic too has been occupying since his genocide trial began, Plavsic was flanked by uniformed UN guards.
She left the court without speaking after sentence was passed.
Plavsic is the only woman among more than 100 people indicted for war crimes in former Yugoslavia.
Last year she admitted that she had "publicly rationalised and justified the ethnic cleansing of non-Serbs".
The UN prosecutors had demanded a sentence of 15 to 25 years' imprisonment, but Mr May and his Jamaican and Korean colleagues ruled that would give her insufficient credit for voluntarily surrendering and pleading guilty, and for her role in promoting peace.
They also rejected the prosecution argument that her refusal to testify against Mr Milosevic should be held against her.
The last time Plavsic was in the dock a succession of witnesses testified that she had played a constructive role in promoting peace by backing the 1995 Dayton agreement.
They included Madeleine Albright, the former US secretary of state, and Elie Wiesel, the Holocaust survivor and Nobel peace laureate.
It was a remarkable transformation for a Serb hardliner who was photographed in 1992 kissing the infamous Zeljko Raznatovic - better known as Arkan - whose paramilitary "Tigers" carried out brutal killings of civilians.
But Plavsic was not afraid to challenge fellow Serbs whom she saw as traitors. There was no love lost between her and Mr Milosevic's wife, the influential Mirjana Markovic, who called her a "female Mengele".
Her international reputation improved when she fell out with Radovan Karadzic and replaced him as president of the Bosnian Serb Republic after Dayton.
Last October, in a dramatic turnabout, she changed her plea from innocent on eight counts, including genocide, to guilty of one count of persecution: a crime against humanity which carries the penalty of up to life in prison.
The prosecutors dropped the other charges and she was provisionally released.
She will remain in detention in the UN wing of the nearby Scheveningen prison - often referred to as the "Hague Hilton" - before being sent to one of the nine European countries which jail convicted war criminals.
Plavsic has long seemed philosophical about her fate.
"What do 10 years of prison mean to me?" she asked last year. "For me it is tantamount to a life sentence."
An estimated 200,000 people were killed in the three and a half years of the Bosnian war - the worst carnage in Europe since the second world war - as Serbs tried to drive Muslims and Croats from Serb-dominated areas and create a greater Serbia.
Professor to prisoner
· Born Tuzla, Yugoslavia, July 1930. Divorced. No children
· Studied at Zagreb University and won a Fulbright scholarship to study in the US
· Professor of natural sciences and dean of faculty at the University of Sarajevo
· Joined the Serbian Democratic party, led by Radovan Karadzic, in July 1990. Said that Muslims were 'a genetic defect on the Serbian body'
· Served as the Serbian representative on collective presidency of Bosnia and Herzegovina from November 1990 to December 1992
· Became the deputy president of the Serbian Republic, taking over from Karadzic, in 1996. She received the backing of the west as she campaiged to oust his hardline allies. Key figure in implementation of 1995 Dayton peace accords ending the Bosnian war
· Surrendered to the Hague war crimes tribunal in January 2001
· Changed plea to guilty in October 2002, a decision which her lawyers said showed 'her remorse fully and unconditionally'