A Turkish court has ordered the release of Taner Kilic, chair of the Turkish chapter of Amnesty International.
Kilic had been in prison since June 2017, when he was arrested for allegedly having links to a group accused of being behind the 2016 attempted coup.
"It's a great victory for the human rights movement in Turkey and it's gonna give us more strength to go on and campaign for the acquittal of everyone in this case," Andrew Gardner, senior adviser on Turkey for Amnesty International told Al Jazeera.
"We're all incredibly happy. This is what we campaigned for, for the last eight months."
Family members and colleagues were on the way to Izmir, the city where Kilic was being held.
Authorities say Kilic was using ByLock, an encrypted communication software which the government says is used by members of a group led by Fethullah Gulen, a US-based, self-exiled religious leader who the government blames for last year's coup attempt.
Both Kilic and Amnesty Turkey have strongly denied the allegations.
"It's a completely baseless case that was brought against them because they are human rights defenders," Gardner told Al Jazeera.
Despite Kilic's release, the case against him will continue in June this year. Pending this hearing, Kilic has been given a travel ban, prohibiting him from leaving Turkey.
Kilic's arrest was part of a purge by the Turkish government in the wake of a failed coup attempt in July 2016. Tens of thousands of people were imprisoned and dismissed from their jobs.
Local and international rights groups have accused the government of using the coup attempt as a pretext to silence opposition in the country.
The government has said that the purges and detentions are aimed at removing supporters of Gulen from state institutions and other parts of society.
Gardner said despite Kilic's release on Wednesday, Amnesty would continue fighting for both him and many others in the country.
"The fact is that over 100,000 officials have been dismissed from their jobs without due process, and there are more journalists in prison in Turkey than anywhere in the world," he said.
"Our work for them will go on and our work for everyone who has been unfairly imprisoned in Turkey will continue," Gardner added.
"But tonight we'll take some time off to celebrate Taner's release."