The vaccine was previously authorized for use by Health Canada in only adults over the age of 18.
The two-shot vaccine is not yet authorized in the United States to treat children between 12 to 17, but was recommended for approval in Europe and has been cleared in the UK.
While most children develop mild or no symptoms with COVID-19, they are still able to spread the virus and some remain at risk of becoming seriously ill.
Canadian health authorities said they will continue to monitor the safety of the vaccine and take action if any concerns are identified.
The Washington Post had reported last week that U.S. health officials are reviewing Canadian data that suggests a higher risk of a rare heart condition in younger adults than the Pfizer-BioNTech vaccine, citing people familiar with the review.