Alek Minassian, 25, was not previously known to authorities, police said, adding that the incident appeared deliberate but no motive was clear.
Mr Minassian was arrested after a tense standoff with a police officer.
Canadian Prime Minister Justin Trudeau called the incident a “senseless attack and a horrific tragedy”.
The officer who arrested Mr Minassian was praised for not opening fire during a standoff with the suspect, who claimed to be armed and pointed an object at the officer.
Video broadcast on CBC News showed the suspect shouting “kill me”, while the officer instructs him to get down.
When he said he had a gun, the officer said: “I don’t care. Get down.” He was then arrested without any shots being fired. He is due in court at 10:00 local time (14:00 GMT) on Tuesday.
Speaking at a news conference on Tuesday, Mr Trudeau praised the police officers involved, who he said “faced danger without a moment of hesitation”.
Police said the suspect in the van mounted the kerb on Yonge Street between Finch Avenue and Sheppard Avenue at about 13:30 local time (17:30 GMT) on Monday and drove into pedestrians along a 1km (0.6-mile) stretch.
Reza Hashemi, who owns a video shop on Yonge Street, told the BBC he heard screaming on the other side of the road. He said the van was repeatedly mounting the pavement and running into people.
One witness told City News that the driver was “hitting anything that comes in the way”.
“People, fire hydrants, there’s mail boxes being run over,” said the unnamed man, who said he was driving behind the van during the incident.
As the van continued, the man said he sounded his horn to try to warn pedestrians. “I witnessed at least six, seven people being hit and flying in the air, like killed, on the street,” he said.
Suspect Alek Minassian is due to appear in court on Tuesday morning
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