Contract negotiations continue between the union representing Canada Border Services Agency workers and the federal government.
It comes as nearly 9,000 members across the country began work-to-rule action at 6 a.m. Eastern Time on Friday.
The unions representing the workers served strike notice to the federal government earlier this week.
They warn that travellers should expect long lineups and lengthy delays at border crossings and airports.
Employees want better protections against what they describe as toxic workplace culture and greater parity with other law enforcement agencies. They have been without a contract for more than three years.
The sweeping job action comes just days before the Canadian border is set to reopen to fully vaccinated U.S. citizens next Monday.
