Liu Xia's friend, meanwhile, told Kyodo News that she wanted to leave China together with her younger brother, but that was not permitted. I'm grateful for those who cared about her and helped her all these years.
Rights groups and Western nations had been raising pressure on Beijing over Liu Xia in recent months, as fears grew among rights groups that she might never be able to leave and live overseas, a wish she had made clear.
This file photo taken on October 22, 2002 shows Chinese dissident and Nobel Peace laureate Liu Xiaobo (L) and his wife Liu Xia (R) posing for a picture in Beijing.
Chinese authorities had consistently maintained Liu was free but imposed severe restrictions on her movement and kept her under constant surveillance.
News of her release came just a day after German Chancellor Angela Merkel and Chinese Premier Li Keqiang met in Berlin, stressing their shared commitment to free trade in what some observers saw as a message to U.S. President Donald Trump.
The German embassy had offered in April to help Liu Xia travel to Germany but the move did not take place.
Liu Xiaobo was jailed for 11 years in 2009 on subversion charges after co-authoring a petition known as Charter 08 calling for sweeping political reforms in China.
She has been under de-facto house arrest since 2010 after her husband, Liu Xiaobo was awarded the Nobel peace prize in absentia for his activism in China. During this visit, Merkel had reportedly pressed China on human rights - particularly about the case of Liu Xia.
Beijing has always insisted that she is a free citizen.
"This is fantastic news, something we have all been hoping against hope for a long time", said Hu Jia, a family friend and Beijing-based activist.
Liu Hui is in China.
The Chinese foreign ministry confirmed Liu Xia's departure, according to AP.
The Chinese government has criticized calls by Western governments for Liu's release, saying that foreign countries were making "improper remarks" over local issues.
Ms Liu was never charged but was largely confined to her Beijing home.
As her brother remains on the mainland, Chinese authorities would "make sure that Liu Xia's behaviour overseas will meet its expectations", said Wu'er.
In an emotional phone call with Liao recently, Liu said, "They should add a line to the constitution: "Loving Liu Xiaobo is a serious crime - it's a life sentence". Government security guarded her home at all hours and restricted her contact with the internet and foreigners. "Dying is easier than living - there is nothing simpler for me than to protest with death".
A poet, a painter, and a photographer herself, Liu Xia's writings are inward-looking, wrote Ian Johnson, noting that her poems are laden with symbols associated with the struggles of dissidents in China, such as birds and the empty chair that has come to to represent Liu Xiaobo.
After Liu Xiaobo's funeral in July a year ago, his widow did not return to her home in Beijing until September, as calls grew from the worldwide community and supporters for her release.
Her husband was only the second Nobel Peace Prize victor to die in police custody, a fact pointed to by human rights groups as an indication of the ruling party's increasingly hard line against its critics.