Taner Kilic had been jailed for a year on charges of supporting the US-based cleric whom Ankara blames for a July 2016 failed coup.
An Istanbul court on Wednesday ordered the release of Amnesty International's Turkey chair who has spent more than a year in jail over alleged links to the 2016 failed coup, the rights group said.
First detained in June 2017, Taner Kilic should be released in the next hours, Amnesty's Turkey researcher Andrew Gardner told AFP.
Kilic, who is being held in the western city of Izmir, is accused of links to the Fetullah Terrorist Organisation (FETO), the group behind the defeated 2016 coup bid in Turkey.
"We are overjoyed at this news," said Kumi Naidoo, Amnesty International's new Secretary General.
Kilic's release is set to be conditional, with the charges standing and him remaining on trial.
TRT World's Melinda Nucifora has more from Istanbul.
Kilic was arrested on June 6, 2017, on what Amnesty describes as the "baseless charge" of belonging to a terrorist organisation.
Authorities accused Kilic of having an encrypted messaging application on his phone in August 2014 called ByLock, which Ankara says was especially created for Gulen supporters.
Kilic could face up to 15 years in jail if found guilty.
Kilic is on trial with 10 other rights activists, including Amnesty's Turkey director Idil Eser, who were detained on terror charges after holding a workshop on an island off Istanbul.
The other 10 were all released last year, although they remain charged and on trial.