Nadir Syed was arrested hours after buying a chef's knife in November 2014, days before Remembrance Sunday - held on the second Sunday of November to commemorate the contribution of British and Commonwealth soldiers in the two World Wars.
Woolwich Crown Court heard how the 22-year-old from Southall area of west London had been inspired by ISIS leaders urging attacks on Western targets, including police and soldiers.
Prosecutor Max Hill told the court he was actively searching for knives of "sufficient quality to source an attack".
The prosecution said the fatwa that inspired Nadir Syed urged followers to rise up against westerners and "rig the roads with explosives for them. Attack their bases. Raid their homes. Cut off their heads".
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"This fatwa, and the worldwide attacks that followed, inspired the defendant to plan his own attack in this country, emulating the attack on Lee Rigby carried out by Michael Adebolajo, who he considered to be a mujahid or Islamic fighter," Hill said.
They will be retried.
The jury returned a majority verdict on Syed after more than 50 hours' deliberation and he will be sentence on a later date, yet to be confirmed.
Syed had also tried to travel to Syria to fight with ISIS militants but had been stopped from leaving the country in January 2014, the court heard.