Muslim protester Mizanur Rahman has been found guilty of stirring up racial hatred during a march against the publication of an Islamic cartoon.
But the Old Bailey jury could not reach a verdict on another charge of inciting murder.
British-born Rahman, 23, was filmed by police chanting "Bomb, bomb France, nuke, nuke France" and calling for the Mujahideen to massacre UK and US troops.
The web designer had earlier been caught on camera carrying placards reading "Behead those who insult Islam" as he marched through central London.
Rahman was one of the leaders of the mass rally sparked by the publication of the cartoon in a Danish newspaper.
Protest in Denmark
Protest in Denmark
The jury of eight women and four men had spent nine hours deliberating the case during the five-day trial.
Rahman has now been remanded in custody to await sentence.
Many Muslims believe any visual representation of the Prophet Mohammed is forbidden.
Protesters had gathered at the Regent's Park mosque in London on February 3 before marching on the Danish Embassy in Sloane Street to burn the country's flag.
Rahman grabbed a microphone and began ranting against those who "insult" Islam.
He told the crowd Muslims did not want democracy imposed on Iraq - and urged insurgents to step up attacks on Coalition forces.
He said: "The Mujahideen will destroy them and their freedom in Iraq and Afghanistan, in Fallujah and Baghdad
"We want to see them coming home in body bags. We want to see their blood running in the streets of Baghdad."
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