Sophie Gregoire Trudeau recently returned from London and experienced flu-like symptoms, so she was tested for the coronavirus, the prime minister's office said earlier on Thursday. The test came back positive, it said in the evening.
"The Prime Minister is in good health with no symptoms. As a precautionary measure and following the advice of doctors, he will be in isolation for a planned period of 14 days," an official statement said. Sophie will be in quarantine for 14 days.
"The Prime Minister will continue to fully assume his duties and will address Canadians tomorrow."
In a personal note, Sophie said she was "experiencing uncomfortable symptoms of the virus," adding that she "will be back on my feet soon."
Canada reported 145 new case of the virus, a three-fold gain from a week ago. There has been one death. Seven of Canada's 10 provinces have recorded infections.
Ontario, the most populous province, reported 17 new cases overnight, a 40% jump. To contain the virus, authorities ordered all schools to close from Saturday to April 5.
Globally, more than 127,000 people have been infected by the sometimes deadly respiratory illness COVID-19.
In a blow to hockey-obsessed Canadians, the National Hockey League suspended its season because of the outbreak, although it said its goal was to resume play "as soon as it is appropriate and prudent," so teams can compete for the Stanley Cup championship.
With the Canadian dollar at a four-year low against its U.S. counterpart and stocks plunging, the Bank of Canada announced measures to inject liquidity into the market.
Working from home on Thursday, Trudeau spoke with U.S. President Donald Trump, British Prime Minister Boris Johnson, Italian Prime Minister Giuseppe Conte and joined a special cabinet meeting on the coronavirus by phone, his spokesman said on Twitter.
The Pacific province of British Columbia, north of Washington state, advised against all non-essential foreign travel, including to the United States. Washington is one of the worst-affected states.
Any warning that involves the United States is politically sensitive, given the two countries' 5,525-mile (8,890-km) shared border and Canada's overwhelming reliance on bilateral trade.
"This is really important ... the evolving situation both in the United States and globally is a risk for all of us," British Columbia's provincial chief medical officer, Bonnie Henry, told reporters.
Alberta's chief medical officer, Deena Hinshaw, banned gatherings of more than 250 people and canceled all international events. Hinshaw also discouraged foreign travel.
Quebec, which has recorded 13 cases, has banned all indoor events with more than 250 people and said people returning from any foreign country should self-isolate for 14 days. Health and education public-sector workers who travel abroad will be required to self-isolate.
Separately, Canadian authorities canceled the JUNO music awards, Canada's version of the Grammys, and Toronto's annual St. Patrick's Day parade was suspended.
Ottawa committed C$1 billion ($723 million) on Wednesday toward bolstering the healthcare system and limiting the impact of the virus, while Ontario said on Thursday it had set aside C$100 million in "contingency funding."
On Thursday, Alberta Premier Jason Kenney said the public health crisis alone would cost the country "well north of C$10 billion."