Oumaima Chouay, 27, was arrested upon her arrival at Montreal’s Trudeau Airport. Ms Chouay is accused of four crimes including leaving Canada to participate in the activity of a terrorist group, the Royal Canadian Mounted Police said in a statement.
Kimberly Polman, 50, was also arrested upon her arrival in Canada, her lawyer Lawrence Greenspon told The National.
About 43,000 foreign men and women linked to ISIS are currently being kept in squalid camps and prisons throughout north-east Syria.
Canada has been reluctant to repatriate citizens associated with the terror group despite pleas from families and the international community.
Earlier this year, UN human rights experts called on Canada to repatriate Ms Polman because of poor health.
Ms Polman allegedly travelled to Syria in 2015 at the behest of her husband, whom she had met online.
“Victims or potential victims of trafficking should not be placed in situations that expose them to multiple forms of abuse,” said UN experts at the time.
“The failure of their home state to protect individuals in such situations perpetuates and contributes to further victimisation of those who have already experienced violence and trauma.”
Alexandra Bain, who runs Families Against Violent Extremism, an organisation that has been advocating on behalf of some of the Canadian women and children still stuck in north-east Syria, estimates that there may be as many as 50 Canadians in the region, more than half of whom are children.
“Canada has really fallen short,” Ms Bain told The National.
“It presents itself as supporting human rights and the rights of the child. Well, where are the human rights here? Where are the rights of the child here?
“I'm really, really disappointed with Canada.”
In addition to Ms Polman and Ms Chouay, two children were also brought back to Canada, the government reported.
“The safety and security of Canadians, both at home and abroad, is a top priority of the Government of Canada,” the government tweeted from its official Canada in Syria account.
The tweet went on to thank the US for “assistance with the operation”.