Supporters broke into applause as the judge announced that Aya Hejazi, her husband Mohamed Hassanein and six others were found not guilty on charges including human trafficking, sexually exploiting children and failure to properly register a non-governmental organization.
Hejazi, who co-founded a charity which helps Cairo street children, was arrested in May 2014 and has been in jail pending the outcome of the trial.
She and her co-defendants denied the charges and rights groups raised concerns they were not being allowed a fair trial.
Hejazi’s supporters say she was targeted at a time when authorities were cracking down on civil society groups and protests, trying to paint protesters as paid agents of foreign entities.
When the verdict was read, supporters jumped up and cheered. The defendants sang as they left the courthouse for a prison vehicle that was to take them back for their final days in detention.
Taher Aboelnasr, Hejazi’s lawyer, said the prosecution could appeal the verdict but that would not prevent the defendants’ release, which he said should happen this week.
The verdict “must be implemented,” Aboelnasr told reporters, adding that the defendants would be released “probably on Tuesday or Wednesday”.
Speaking to reporters outside the courtroom after the verdict, Hejazi’s mother Naglaa Hosny said she was thrilled for her daughter and son-in-law.
Hejazi’s mother said the couple was considering starting another charity but that she hoped they would instead go back to school.
“Right before she got arrested, she had applied for the American University in Cairo and was accepted” into a community psychology program, Hosny said.
“She really wanted to work with street kids and the communities which produce the street kids,” said Hosny.
The case caused widespread concern, with Human Rights Watch (HRW) last month calling the trial “nothing less than a travesty of justice”.
“Defendants have been unable to meet privately with lawyers, hearings have been repeatedly adjourned for long periods, while the court has routinely rejected, without explanation, numerous requests for release on bail, resulting in what appears to amount to arbitrary detention,” HRW deputy Middle East and North Africa Joe Stork said at the time.
A senior White House official told reporters ahead of Egyptian President Abdel Fattah el-Sisi’s Washington visit last month that administration officials would raise Hejazi’s case during the trip.
The prosecution alleged that children were sexually abused at the offices of the Belady Foundation, which Hejazi co-founded with her husband in 2013.
The defense argued that evidence may have been tampered with and several prosecution witnesses later recanted their testimonies.