Choudary and his co-accused Mohammed Rahman are each handed prison sentences of five years and six months.
His co-accused, Mohammed Mizanur Rahman, was given the same jail term. The maximum sentence was 10 years.
When the sentence was handed down, there was a shout of “Allahu Akbar” from Choudary’s supporters in the public gallery, before the court was cleared.
Choudary became Britain’s best-known Islamist preacher, and his followers were implicated in numerous plots around the world.
During the trial, the jury were shown pictures of Choudary and Rahman at a demonstration outside the Lebanese embassy in central London in April 2014, before the so-called Islamic State group was proscribed.
Some of the crowd were holding placards which had writing at the bottom which said: “Islamic State Is Solution” with the first letter of each word underlined to make ISIS.
The Old Bailey heard he had used online lectures and messages to encourage support for IS.
Statements from Rahman in November 2013, under the Twitter name @AbuBaraaUK said: “Re-establishing the Khilafah (Caliphate) is a compulsory duty on all Muslims.”
Another, on Facebook, said: “If anyone says martyrdom operations are not allowed … do not take ilm (religious advice) from him.”
Judge Mr Justice Holroyde told both defendants: “You expressed contempt for the values by which we live.”
He said Choudary, 49, and 33-year-old Rahman were free to support IS, but not free to invite others to do so. “It is a crime,” he said.
And he added that the absence of any direct link with those carrying out acts of terror for IS did not mean their crime was not serious.
The judge described Rahman as a “hothead” while Choudary was more calculating and more experienced.
“You are both mature men and intelligent men who knew throughout exactly what you were doing,” he said. “You are both fluent and persuasive speakers.”
Commander Dean Haydon, head of Anti-Terrorism Command, said the pair had radicalised others, and encouraged them to join terror organisations.
“If I look at both these individuals they are connected to and associated with proscribed organisations both here and overseas,” he said.
“From what we know from the evidence presented, they were certainly in contact with terrorists, again overseas.
“So the sentence today is certainly welcome, and it’s a credit to the hard work over many, many years that has gone into monitoring preachers of hate, here in the UK but also, their wider connections overseas.”
He added that work must be done with communities to make sure that people don’t step into their shoes and back fill their positions.
Addressing the judge, Choudary’s lawyer, Mark Summers QC, said “I hope my lord will accept that the evidence in this case shows over the course of 20 years Mr Choudary has done his best, determined to stay within the law, acting on the boundaries of it but staying within the law.
“In the commission of these offences Mr Choudary believed he was still within the law, although ignorance of the law is no defence.
“But he has had time to reflect and on reflection would have done things differently had he known the boundaries of the law.
“He is determined not to cross those boundaries in the future.”
Mr Summers said he feared for Choudary’s mental health if he was held in solitary confinement in jail.
[Source:-Sky News]