Rory Amon was found not guilty of four counts of child rape, two counts of attempted child rape and two counts of indecent assault of a child on Monday after three days of deliberations.
However, jurors sitting in the NSW Supreme Court trial could not reach a verdict for further charges of rape and indecent assault of a child.
The deadlocked jury was discharged.
Amon kept his eyes downcast and maintained a blank expression as the jurors found him not guilty of eight charges.
The former Liberal MP was later seen stepping from the dock with a large grin, hugging his barrister.
Outside court, he remained silent and stared ahead as he moved with supporters through a throng of reporters.
The 36-year-old had pleaded not guilty to all charges and denied any criminal conduct.
He will be arraigned on April 10 before a possible retrial.
Amon admitted meeting the teen once for sex in 2017 but denied claims of a second meeting soon after.
He testified he held an honest and reasonable belief the teen was over the age of 16.
The pair met online on an adults-only website.
The trial was told the boy inflated his age when signing up to the gay hook-up app and again while talking with Amon.
Amon, then 27 and aspiring for a life in politics, and the boy moved their discussion to Snapchat, where explicit messages and images were sent, before meeting in person.
The jury heard Amon turned up to the teen's apartment block, wearing a tracksuit and ugg boots, before the pair moved to a small, dirty bathroom under the building.
Amon had seen the teen in explicit photos, under street lights and then in the lit bathroom before the light was turned off, the Crown argued.
That would have made it obvious to Amon the youth was under 16, the jury was told.
"He told me he was 17 and nothing I saw changed that belief," Amon testified.
Arrested in August 2024, Amon pleaded not guilty to five counts of having sexual intercourse with a child, two counts of attempted sexual intercourse with a child and indecent assault charges.
The eight charges he was acquitted of related to the boy's claims of a second meeting with Amon in the car park bathroom in July 2017.
Jurors were told the boy told friends, his mother, a school counsellor and his psychologist about the allegations soon afterwards.
He made a formal complaint to police five years later.
The two briefly reconnected on Grindr in 2022 when Amon sent him more images, including one wearing his volunteer firefighters uniform.
At the time he first contacted the youth in 2017, Amon was working full-time for federal Mackellar MP Jason Falinski.
He would go on to serve two terms on Northern Beaches Council before being elected as the Liberal MP for the state seat of Pittwater in 2023.
The charges killed Amon's fledgling career in state politics, forcing his expulsion from the Liberal party and his resignation after his election in March 2023.
His exit had implications for the state Liberals, which lost the formerly safe seat to a teal independent at the subsequent by-election.
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