That brings the Cambridge, Mass., drugmaker's total order for Canada to 40 million doses.
Shares of Moderna at last check rose 4.1% to $158.75.
The company said it remained on track to be able to start delivery of its covid-19 vaccine candidate following regulatory clearance by Canadian health authorities.
Moderna has already begun the review process with the ministry and intends to seek emergency-use listing with the World Health Organization.
"This increased supply agreement from the Canadian government today reaffirms the confidence in our covid-19 vaccine candidate, and we appreciate our collaboration with the Canadian government as with many other governments and other key partners around the world,” Chief Executive Stephane Bancel said in a statement.
The Canadian vaccine supply will be sourced from Moderna’s European production capacity, with its strategic manufacturing partner Lonza in Switzerland, and ROVI in Spain for fill-finish services, the company said.
Last week Moderna added four million more doses to its covid-19 vaccine to Israel, on top of two million already supplied, according to a company statement.
Moderna last week also filed for marketing clearance from European health authorities for its coronavirus vaccine.
Moderna, which reported a 100% efficacy rate against severe forms of covid-19 from late-stage trials of its mRNA-based vaccine on Nov. 30, will likely get a decision from the European Medicines Agency on Jan. 12, officials indicated.