Ryan Giggs - leaving court on Wednesday - could now face a retrial
The 48-year-old denied headbutting ex-partner Kate Greville, 38, during a row at his home in November 2020.
He also denied controlling behaviour, as well as assaulting Ms Greville's sister Emma, 26, at Manchester Crown Court.
Any retrial will not take place until at least 5 June 2023, the judge said.
Mr Giggs' head dropped when he heard how long it could take for the case to conclude.
The jury had failed to reach a verdict on any of three charges against Mr Giggs, who was Wales manager until he resigned in June, after deliberating for 22 hours and 59 minutes.
The jury was made up of 11 people - seven women and four men - after one of the original 12 jurors had fallen ill.
Judge Hilary Manley asked jurors if they had reached a verdict on any counts on which a majority of 10 to one had agreed.
The foreman of the jury answered: "No."
The former Wales manager had denied all charges
Asked if there was any "realistic prospect" of them reaching verdicts if given more time, the foreman again answered: "No."
She then thanked the jurors and discharged them, warning them not to discuss the case as there may be another trial of the case in the future.
Judge Manley said "it was clear they had striven hard to reach verdicts" and should not feel "dispirited".
The former Manchester United footballer had been on trial for four weeks.
The Crown Prosecution Service has a week to decide whether to pursue a retrial.
If this happens, a new jury would be sworn in, which will hear the evidence as part of a new trial.
Mr Giggs has been released on bail until 7 September, when what happens next in the case will be discussed at a hearing.
Mr Giggs could go on trial again next year
At the start of the trial, Peter Wright QC, prosecuting, called it a story of "control and coercion" of a woman who thought she was "loved and respected".
He said the former player's relationship with Ms Greville was "punctuated by acts of violence and volatility".
She had claimed she became "a slave to his every need and every demand".
The court also heard her claim that Mr Giggs had dragged her naked across the floor of a hotel room in Dubai in September 2017 and threw her and her belongings into the corridor, bruising her arm in the process.
But jurors also heard she referred to the bruise as a "sex bruise" in a message to him.
Mr Giggs admitted to being unfaithful in relationships but, when asked if he had ever physically assaulted a woman, he said "no", adding that he had never set out to control or coerce a woman.
The trial was told of the alleged assault on 1 November 2020 at his home in Worsley, Greater Manchester, where the couple returned following a row at dinner in which she accused Mr Giggs of messaging a string of women.
Jurors heard the pair tussled over their mobile phones, leading to Kate Greville's sister Emma Greville, who was looking after the couple's dog, calling the police.
Giving evidence, Emma Greville said her sister had screamed and fell to the floor and Mr Giggs told Emma Greville it was "her fault" and then threatened to do the same to her.
He denied the accusations and alleged Kate Greville kicked him in the head.
A social media post brought to the attention of Judge Manley on 10 August, a couple of days into the trial, has been referred to the Attorney General as a possible Contempt of Court, she said.
-- Courtesy of BBC Sport