The war criminal was convicted of genocide and crimes against humanity for his part in the atrocities committed during the 1992-95 war.
In a statement, Foreign Secretary Dominic Raab said: "Radovan Karadzic is one of the few people to have been found guilty of genocide.
"He was responsible for the massacre of men, women and children at the Srebrenica genocide and helped prosecute the siege of Sarajevo with its remorseless attacks on civilians.
"We should take pride in the fact that, from UK support to secure his arrest, to the prison cell he now faces, Britain has supported the 30 year pursuit of justice for these heinous crimes."
Karadzic was convicted in March 2016 over genocide, crimes against humanity and war crimes as the political mastermind behind Serb crimes in the 1992-95 Bosnian war, a conflict which claimed the lives of more than 100,000 people and displaced 2.2 million others.
The UN court in The Hague found him guilty of ten out of 11 charges, including one of genocide over the massacre of around 7,000 Bosnian Muslim boys and men at the town of Srebrenica in July 1995.
He was sentenced to 40 years, later increased to life.
In Serbia some still regard Karadzic as an unwanted reminder of a shameful period in Serb history, while others view him as a hero and a patriot who stood up for the rights of Serbs during a period of violence and confrontation.