Thomas Barley, 27, pleaded guilty to arson with intent to endanger life after stoking a fire in a bin by an entranceway to a hotel at Rotherham in northern England on August 4.
Prosecutor Elisha Kay said Barley added wood to an already-flaming industrial bin that had been placed in front of a fire door of the hotel while staff and guests sheltered inside.
Kay said hotel staff barricaded themselves in a panic room and "thought they were going to burn to death".
Barley, who also pleaded guilty to violent disorder and possessing an offensive weapon, was sentenced at Sheffield Crown Court by Judge Jeremy Richardson, who said Burley's actions were "suffused with racism from beginning to end".
Richardson said Barley had been encouraged to join the disorder "by malicious and ignorant posts" on social media.
"You were a leading participant in ignorant, racist attempts at mob rule," the judge said on Friday.
The hotel was targeted by about 400 people during days of rioting involving violence, arson and looting as well as racist attacks after three young girls were killed in the northern English town of Southport on July 29.
The attack was initially falsely blamed on an Islamist migrant following online misinformation.
A protest in Southport the day after the killings turned violent, and riots spread across the country, leading to about 1300 arrests and about 200 people being jailed.
The longest sentence over the riots had until Friday had been six years for violent disorder.
Others have been charged for inciting racial or religious hatred online.
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