Tommy Robinson will be freed on bail after winning his Court of Appeal hearing.
He was sentenced to ten months in May for contempt of court, and a further three months for breaching a previous suspended sentence.
The jail time came after he filmed people outside Leeds Crown Court who were involved in a trial subject to reporting restrictions.
He used social media to broadcast the footage.
Lord Chief Justice Burnett announced his ruling today after the Court of Appeal hearing, in which Robinson - real name Stephen Christopher Yaxley-Lennon - sought to overturn the contempt of court conviction.
Robinson, 35, will face a re-hearing on the charges at a later date.
The judge said the conviction was “flawed” and “rushed” and summarised by saying: “"Once the appellant had removed the video from Facebook, there was no longer sufficient urgency to justify immediate proceedings."
The video posted by former English Defence League leader Robinson was viewed around 250,000 before being removed.
He admitted contempt of court at the original trial.