Former boxing champion Anthony Small spoke out against Coca-Cola and McDonald's as he called for attacks on the West on YouTube, a court has heard.
Mr Small, 36, who converted to Islam in 2007, is accused of encouraging acts of terrorism in the Eid message he posted on his account on 12 September 2016.
He "implored Muslims to take violent action against the West", prosecutor Karen Robinson told the Old Bailey.
Mr Small denies the charges.
On his YouTube channel, Mr Small described himself as "a former professional champion boxer who now works to take mankind out of the oppression of democracy and liberating themselves with Islam/Sharia".