The former speaker of Tunisia's dissolved parliament has been released after appearing in court on Thursday as part of a case involving money-laundering and “incitement to violence”, his lawyer said.
The party dominated Tunisian politics for a decade until President Kais Saied's consolidation of power in July last year.
Other Ennahdha members are also facing prosecution over suspicious transactions involving Instalingo, a digital production firm.
The company has been under investigation since last year for allegedly “plotting against state security” and inciting violence.
After a 14-hour hearing, the investigating judge released Mr Ghannouchi, his lawyer Sami Triki said.
He said Mr Ghannouchi would be prosecuted in this case, but that no date for the next hearing has been set yet.
The 81-year-old had arrived at court in the coastal city of Sousse, where he told journalists the case was an “empty file” and an “invented problem”.
“This is trumped up and aimed at distracting the Tunisian people from the real problems we're facing,” he said.
Mr Ghannouchi has harshly criticised Mr Saied's decision to sack the Ennahdha-supported government and seize full executive authority.
Mr Saied also dissolved the parliament and pushed through a constitution giving his own office almost unlimited powers.
Mr Ghannouchi and other Ennahdha officials are also on trial in a separate case, known as the “shipment of jihadists” to conflict zones, which has been at the heart of the political debate for years and has recently resurfaced.
Ennahdha denies all the charges against its members.
In July, judges froze Mr Ghannouchi's Tunisian bank accounts and those of several relatives and members of his party.
That came after a court issued a travel ban against him in May as part of an inquiry into the 2013 killings of two prominent left-wing figures.