Several Western diplomats tried to visit her at her Beijing apartment in May amid concerns over her psychological health but were refused entry without explanation. In a letter published previous year, Liu wrote she was "going mad" in her isolation, according to the AFP news agency. Liu Xia, though never formally charged with a crime, had been under strict house arrest. The first, Carl von Ossietzky, died from tuberculosis in Germany in 1938 while serving a sentence for opposing Adolf Hitler's Nazi regime. Thanks to everyone who has helped and cared for her these few years.
"If I can't leave, I'll die in my home", Liu Xia had said during a recent phone call with her close friend Liao Yiwu, a writer who documented their conversation in an essay published in May.
The move comes a day after Chinese premier Li Keqiang met German Chancellor Angela Merkel.
Exiled dissident Wu'er Kaixi, speaking in Taipei, told AFP he was "glad" Liu Xia could leave China but also voiced concerns about her brother.
China on Tuesday allowed Liu Xia to fly to Berlin, ending an eight-year house arrest that drew worldwide criticism and made the soft-spoken, chain-smoking 57-year-old poet with a shaven head a tragic icon known around the world. Occasionally, she could write to or call friends, reports said.
A Chinese foreign ministry spokeswoman, Hua Chunying, said Liu left for Germany to seek "medical treatment on her own accord".
Rare images of Liu Xia were released by the authorities previous year as she cared for Liu Xiaobo in his final days fighting liver cancer in a hospital under police custody.
"The lesson of Liu Xia and her courageous husband, the late Nobel Peace Prize victor Liu Xiaobo, who was murdered by the Communist Chinese regime, is simple yet powerful: darkness fears light and mendacity fears truth, so tyrants can not tolerate either", he continued. "If I can't leave, I'll die in my home", she said.
Since President Xi Jinping took office in March 2013, China's government has tightened its control over society and stepped up its campaign against independent activists, lawyers, and others deemed a threat to the Chinese Communist Party.
The Chinese government permitted the blind, activist Chen Guangcheng to travel to NY after he escaped from house arrest and hid for six days in the U.S. Embassy in Beijing. In 2009, he was sentenced to 11 years in prison. Supporters said this was done because of the attention Nobel victor Liu Xiaobo received. Su Yutong, a family friend based in Germany, also confirmed her departure.
At the start of her house arrest, Liu Xia posted regular wry updates on Twitter for her concerned friends.
In turn, Liu Xiaobo lamented the political web in which Liu Xia had become entangled.
But for nearly a year that wish has remained out of reach, as she has remained under house arrest in her residential compound in Beijing, where friends said she was losing her will to live.
Liu faced daily restrictions on movement and surveillance even after her husband's death, although Chinese authorities maintained she was free.
"Liu Xia never gave up on her wrongfully imprisoned late husband, and for this she was cruelly punished", said Patrick Poon, China Researcher at Amnesty International, in response to the news Tuesday.
"Liu Xia might not be able to speak much for fear of her brother's safety", Poon said.