"I feel like the mother of a bride today," Hijazi's mother, Naglaa Hosny, said.
Hijazi and her seven co-defendants -- including her husband Mohamed Hassanein -- worked for a foundation dedicated to aiding Cairo's street children until May 2014 when its offices were raided.
They were accused of child abuse and human trafficking and have remained in detention since. The other defendants were also found not guilty.
Hijazi's case has garnered international attention over the years -- Human Rights Watch called it a "travesty of justice" in a report released last month and argued that there was virtually no evidence to support the prosecution.
Trial postponed for more than 2 years
"The case was flawed from the beginning when the police raided the Belady Foundation without a warrant and unlawfully detained Aya and Mohammed along with several volunteers and children," said attorney Wade McMullen.
The trial of Hijazi and her husband was postponed for more than two years.
McMullen, managing attorney with human rights advocacy organization Robert F. Kennedy Human Rights, represented Hijazi's family in Washington, working closely with the State Department, former President Barack Obama's administration -- and President Donald Trump's new administration.
He says both administrations played a "critical" role in Hijazi's case and have prioritized the case at the highest levels.
"I do believe that the Obama administration and then the Trump administration were critical to ensure that this judge was able to rule based on the evidence, or lack of evidence, without any higher political influence," McMullen said.
Family expects release soon
Hijazi's family and lawyer expect her to be released "within a week."
They were outside of the courtroom when the judge announced the verdict. "Over the moon is a good way to describe how we felt," said Naglaa. The family was not allowed in court during Hijazi's nearly 20 hearings.
"We would sneak in for only 5 minutes, to see her in the cage," she said, referring to the court cages used to hold defendants during trials in Egypt.
For Hijazi, her time in the cage was the only opportunity to meet her husband. For that reason, Naglaa says, her daughter "loved that cage."
When she wasn't catching up with her husband -- meetings that would occur months apart -- she would be reading a book. Her mother recalls the time Hijazi sat against the wall of the cage reading Maya Angelou's "I Know Why the Caged Bird Sings."
Naglaa also credits the "unknown soldiers" that helped secure her daughter's release, particularly Hijazi's classmate at George Washington University, Chelsea Cowan, who she says went "door-to-door" to "take Aya's case across the ocean."