On Monday, Alek Minassian, 25, was arrested as the suspected driver of a rented van which mounted the pavement on the corner of Yonge Street and Finch Avenue.
Ten people died and another 15 are believed to be injured in the attack.
In court, Minassian wore a white jail jumpsuit and had his hands handcuffed. He showed little emotion.
He was asked to say his name and if he understood an order not to have any contact with anyone injured in Monday's crash scene.
He did not enter a plea to the charges and was ordered to return to court on May 10.
The judge ordered he be detained without bond.
Toronto police are trying to find the motive of the driver.
Minassian, of Richmond Hill, an area close to the attack, was captured in a tense but brief confrontation with officers a few streets away from where the van mounted the pavement and continued for a mile, leaving people bloodied and dead.