The 49-year-old Muslim encouraged backing for the terrorist group in a series of talks posted on YouTube, and recognised a caliphate – a symbolic Islamic state – had been created under an IS leader after it was announced on 29 June 2014, the Old Bailey heard.
Despite being a leading figure in the banned extremist group al-Muhajiroun (ALM), and a series of former supporters going on to be convicted of terrorism, Choudary stayed on the right side of the law for two decades before investigators were able to pin him down.
He now faces a maximum possible sentence of ten years in prison, although judge Mr Justice Holroyde admitted: “There is very little in the way of precedent in the way of sentencing. Although this has been an offence under an Act of Parliament for some time, it’s very far from being one of the most common.”
Choudary and co-defendant Mohammed Mizanur Rahman, 33, were found guilty of inviting support for IS between 29 June, 2014 and 6 March, 2015. The verdicts were delivered on 28 July, but for legal reasons can only now be reported.
As the pair were convicted, Mr Justice Holroyde warned them that they face prison, and said they had only shown “a grudging compliance” to the court.
He added: “You have made your disregard for the court abundantly plain.”
Police pounced after Choudary, along with three other influential radicals, lent their names to an oath of allegiance to IS which was posted on the internet.
The trial heard that the preacher had been the “mouthpiece” of Omar Bakri Mohammed – the founder of the banned extremist group ALM.
He courted publicity by voicing controversial views on Sharia law, while building up a following of thousands through social media, demonstrations and lectures around the world.