The charge came just hours after Justin pleaded not guilty to his arrest in Miami last week via a written pleading. It is the second brush with the law in a week for the singer, who was charged with DUI, resisting arrest and driving without a valid license on 23 January – his arraignment has been set for 14 February.
Justin arrives at the 52 Division of the Toronto police department to face assault charges
"The Toronto Police Service requested that Justin Bieber appear in Toronto today to face an allegation of assault relating to an incident on December 29, 2013," his lawyer said in a statement.
"We anticipate that this matter will be treated as a summary offense, the equivalent of a misdemeanour in the United States.
"Our position is that Mr Bieber is innocent. As the matter is before the court, it would be inappropriate to address the specifics of either the allegation or of our defense at this time."
Toronto police have said that Justin was one of six people picked up by a limousine outside a nightclub in the early hours of 30 December.
The singer prepares to turn himself in
"While driving the group to a hotel, an altercation occurred between one of the passengers and the driver of the limousine," a police statement said.
"In the course of the altercation, a man struck the limousine driver on the back of the head several times.
"The driver stopped the limousine, exited the vehicle and called police. The man who struck him left the scene before police arrived."
After surrendering to police on Wednesday, the singer was charged with one count of assault and is scheduled to appear in court in Toronto on 10 March.
Justin was arrested for a separate incident in Florida last week
Meanwhile, a petition requesting Justin's expulsion for the US has amassed 100,000 signatures, and has been filed on a White House website by a member of the public.
"We the people of the United States feel that we are being wrongly represented in the world of pop culture. We would like to see the dangerous, reckless, destructive, and drug abusing, Justin Bieber deported and his green card revoked," the petition states.
"He is not only threatening the safety of our people but he is also a terrible influence on our nation’s youth. We the people would like to remove Justin Bieber from our society."
It's highly unlikely the petition will work. US immigration law states that an individual's visa can't be revoked unless they have been convicted of a violent crime or sentenced to more than a year in prison. But since it has reached over 100,000 signatures, the White House is required to respond.