Bieber traveled to Toronto to be booked on the charge, which was to happen at a police station later Wednesday, two sources with knowledge of the case told CNN.
This is the 19-year-old pop star's second arrest in a week.
Bieber's representative sent a written statement to CNN on Wednesday night as the singer was inside the police station.
"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," the statement said. "We anticipate that this matter will be treated as a summary offense, the equivalent of a misdemeanor in the United States."
"Our position is that Mr. Bieber is innocent," the representative said. "As the matter is now before the court, it would be inappropriate to address the specifics of either the allegation or of our defense at this time."
Bieber was briefly jailed in Miami on January 23 after he was stopped by a police officer who said he was drag racing in a residential street. He was booked on charges of drunken driving, resisting arrest and driving with an expired license.
Sheriff's detectives in Los Angeles presented evidence this week to the district attorney in their investigation of Bieber's alleged egg attack on a neighbor's house three weeks ago. The prosecutor is expected to decide as early as next week whether Bieber will be charged with felony vandalism for the incident.
Police have not publicly confirmed details of the case against Bieber, but Canada's CBC News reported that Toronto Police were called to the area of Dundas Street West and University Avenue on the evening of December 29 in response to an alleged assault involving Bieber's limousine driver. At the time, it was unclear if the incident was connected to Bieber or a member of his entourage.
The singer had attended a Toronto Maple Leafs hockey game at the Air Canada Centre earlier in the evening, according to the CBC.
Bieber's manager, Scooter Braun, has posted messages on Twitter that appear to be related to Wednesday's arrest:
"for all those asking @JeremyBieber and @pattiemallette love their son. Stop passing judgement on a situation u dont understand. i ask people to be kind and hope for the best in people. not assume the worst. thanks"
Bieber's latest criminal arrest came just an hour after the television debut of his newest video, for his song "Confident."
Egging investigation 'tightening up'
Detectives are "tightening up" their case against Bieber in his alleged egg attack on a neighbor's residence, an investigator said Tuesday.
The neighbor accused Bieber of tossing eggs over a fence and onto the mansion next door on January 9, causing an estimated $20,000 in damage.
A dozen Los Angeles County Sheriff's deputies raided Bieber's $6.5 million home in the exclusive Oaks community in Calabasas, California, two weeks ago, taking the security video system as evidence.
A prosecutor reviewed the security video Monday and asked detectives to do more investigation before a decision is made about charging the pop star with felony vandalism, according to Lt. David Thompson.
Detectives will likely meet again with prosecutors in the Los Angeles County District Attorney's office next week, Thompson said. The district attorney will then decide if a charge will be filed against Bieber.
Bieber's lawyer on Wednesday entered a written plea of not guilty on behalf of Bieber for charges he faces in Miami, according to the Miami Dade County court docket. His attorney also requested a jury trial.
The plea means Bieber will not have to return to Florida for formal arraignment on the DUI, resisting arrest without violence, and driving on expired license charges.
Although Breathalyzer tests suggest Bieber was not too drunk to legally drive when he was pulled over by Miami Beach police early on January 23, it could be two or three weeks before tests are back from the lab that should give a more accurate blood-alcohol reading and could tell if he was high on marijuana.
Bieber blew .011 and .014 in two Breathalyzer tests given to him at the police station, according to a source with knowledge of the results. Florida's legal limit for drivers under the drinking age of 21 is .02. The police report said Bieber failed a field sobriety test given to him at the police station. He admitted to drinking, using marijuana and taking prescription pills, police said.
Although Bieber was not charged with speeding, the arresting officer said it was his reason for stopping Bieber and testing his sobriety.
The head of the exotic car rental company that owns the yellow Lamborghini Bieber was driving said on Saturday that the GPS tracking system in the high-performance car indicated Bieber never exceeded 55 mph in the 15 minutes before the stop.
The Breathalyzer tests and the GPS information could help Bieber lawyer Roy Black in his defense of the singer.
Bieber fled Miami late on January 24, boarding a private jet for a flight to Panama City, Panama. Paparazzi photos showed Bieber strolling along a beach on the Pacific Ocean on Saturday, kicking a soccer ball while others kite-surfed above the waves.
Other photos showed his manager, Braun, and mentor Usher Raymond with Bieber at the Panama resort. His representatives have been silent about the criminal charges, declining to comment to CNN.