The lawyer, Zhang Kai, who is known for defending religious freedoms is thought to have been released on 23rd March 2016.
Zhang Kai was detained on 25th August 2015 and accused of "disturbing social order", stealing and spying, among other crimes.
He has been in detention for six months under "residential surveillance at a designated location" and not had any contact with his family or with lawyers.
It is then thought he was moved to a criminal detention facility.
He was shown on state television at the end of February where he was seen to confess and admit "disturbing social order", "endangering state security" and behaving in an unprofessional manner.
A number of activists have spoken out, saying the confession was forced.
According to a social media message posted by Zhang on WeChat, he has been released and is back in his hometown in Inner Mongolia.
It is not yet clear whether he has been released on bail, and if so, what conditions, if any, there are on his release.
Zhang Kai has given advice, help and information to churches who are facing the forced removal of crosses in Zhejiang Province, an area with a particularly sizable Christian population.
He also defended pastors detained in connection with their opposition to restrictions on their right to freedom of religion or belief.
Zhang Kai is thought to be among more than 300 lawyers and activists, as well as relatives and associates, who have been interrogated, detained, imprisoned and disappeared since July 2015.
Christian Solidarity Worldwide's Chief Executive Mervyn Thomas, said: "We welcome the news that lawyer Zhang Kai has been released and has been able to return home.
"At this point, the conditions of his release are not clear, so we restate our call on the Chinese authorities to allow Zhang his freedom without condition, upholding his right to freedom of movement and association, and all the rights and freedoms guaranteed under international and Chinese law.
"We further express our concern that several of Zhang Kai's fellow lawyers, as well as a number of Zhejiang pastors, remain in detention.
"We urge the Chinese government to protect the rights and safety of those who defend freedom of religion of belief and other human rights in China."