The 36-year-old has spent a year behind bars in Australia after a jury convicted the league player of two counts of sexual intercourse without consent in April 2023 after an earlier guilty verdict was overturned in a separate appeal.
The New South Wales Court of Criminal Appeal quashed Hayne's convictions on Wednesday, on the basis a judge erred in not allowing the complainant to be further cross-examined during the trial.
The appeal court also ruled the trial judge did not properly direct the jury about how to deal with allegations that the complainant had lied.
A third ground of appeal, arguing the now-quashed guilty verdicts were unsafe or unreasonable, was not upheld.
A new trial has been ordered, which would be Hayne's fourth - but whether he faces another trial will be a matter for prosecutors.
A court will consider bail for Hayne, who played for the Parramatta Eels, on Wednesday afternoon.
Hayne was accused of raping a woman in her home on the night of the 2018 NRL Grand Final.
Three separate criminal trials were told the woman, who cannot be identified for legal reasons, changed her mind about having sex with Hayne after realising he had a taxi waiting outside her house.
Hayne's barrister Tim Game, SC, told an appeal hearing in April that the woman deleted messages between herself and Hayne that demonstrated she had initially shown a sexual interest in him.
The ex-player's defence team also argued the woman should have been cross-examined on why she allegedly told police, "If those message get out, I'm f***ed and he will get off."
Judge Graham Turnbull, who oversaw Hayne's third trial, refused requests for the woman to be cross-examined on the statement, saying it carried "almost infinitesimal weight".
Not allowing further cross-examination was one of the successful appeal grounds.
Hayne's quashed conviction followed a hung jury in his first trial in 2020 and a previous appeal overturning the 2021 guilty verdict from his second trial.
