A prosecutor had requested a 12-year term for Stewart Poirier, 53, the Toronto Star reported. Poirier pleaded guilty in October to attempted murder and four counts of arson.
"The circumstances of Mr. Poirier's life are sad and tragic. It's hard not to feel sympathy for Mr. Poirier ... an impulse-ridden man with the brain of a boy," Justice Rebecca Rutherford said. "It's hard to believe such a sad and tragic man can do such damage."
In January 2011 Poirier set fire to a historic building completed in 1888 that once housed the Empress Hotel. The blaze took 125 firefighters to extinguish.
He later told investigators he "got a kick" out of the fire. At the time, he was on probation for two earlier arsons.
Poirier later set fires to other buildings, including one where he was living, and in dumpsters. He also torched a wood chipper owned by the city and left death threats on his probation officer's answering machine.
Investigators say Poirier was physically and sexually abused as a child while he was in an institution. He has spent much of his adult life behind bars.
"He states that he does get some kind of enjoyment out of seeing people suffer," Sheldon Melodick, a forensic neurologist who examined Poirier, said.