He was found in contempt last week for breaching a reporting ban by videoing defendants accused of sexually exploiting young girls outside a courthouse in Leeds, northern England, while jurors were still considering their verdicts.
The former leader of the English Defence League was found guilty last week of breaching a reporting ban by live-streaming footage of defendants arriving at Leeds Crown Court.
Outside the London court, supporters of Robinson, whose real name is Stephen Yaxley-Lennon, booed as news of his sentence reached them.
Why what Tommy Robinson did was put Tommy first - what we did was put the victims firstDame Victoria Sharp told Robinson that the time he previously spent behind bars for the contempt will be taken into account, reducing his sentence to 19 weeks - of which he will serve half before being released.
His lawyer was forced to apologise when he arrived late for court.
The judges also rejected claims by Yaxley-Lennon that he had made checks in the court about reporting restrictions.
Dozens of angry supporters of British far-right activist Stephen Yaxley-Lennon scuffled with police and marched on parliament after he was jailed on Thursday for contempt of court.
In an appearance on the far-right conspiracy theory website InfoWars on Monday, Robinson asked Donald Trump to grant him asylum in the U.S., claiming he faced being killed in prison if he was jailed on Thursday.
Despite Robinson trying to expose the grooming gang he feel foul of the law, it's not known if Robinson was aware reporting restrictions were in place as usually the media are informed of such restrictions when they request the information from the courts.
Despite the shortened term, supporters of the 36-year-old who had assembled outside the court reacted angrily, which resulted in violent clashes with police.
Attorney-General Geoffrey Cox was given leave to relitigate the case, however, which he chose to do - resulting in Robinson being reconvicted, despite his defence team's arguments that his behaviour was "not materially different to the behaviour we see outside courts day in and day" from mainstream media reporters.
Originally he was jailed for 13 months, but was released after 2, following an appeal.
Dame Victoria Sharp, sitting with Mr Justice Warby, said the contempt committed by Robinson was not "deliberate defiance" and he had not meant to "interfere with the administration of justice".
He served two months in jail before being freed after the original finding of contempt was overturned by the Court of Appeal in August 2018.