The father-of-five spent 20 years spreading extremist views, encouraging people to back IS in a series of speeches posted on Youtube.
Police pounced after Choudary recognised a caliphate - a symbolic Islamic state - had been created under an IS leader in June 2014.
The 49-year-old was arrested along with Mohammed Mizanur Rahman, 33, from Whitechapel, east London.
Following an Old Bailey trial, the pair were found guilty of inviting support for IS between June 29 2014 and March 6 2015 and remanded in custody.
Despite being a leader figure in the banned extremist group al-Muhajiroun (ALM), Choudary stayed on the right side of the law for two decades before investigators were able to pin him down as he preached inciting messages to his 32,000 Twitter followers.
Supporters of the 49-year-old have included Michael Adebolajo and Michael Adebowale, the murderers of soldier Lee Rigby, and suspected IS executioner Siddhartha Dhar.