Unifor members across Ontario will board buses Saturday morning and head to a rally in Windsor.
The union said Unifor members from Brampton, Ingersoll, Kitchener, London, Oakville, Oshawa, St. Catharines, and Toronto will join local demonstrators at the Riverfront Festival Plaza at 1 p.m.
Unifor calls on Canadians to rise up against the U.S. tariffs.
"Workers are in the fight of our lives," said National President Lana Payne. "[U.S. President Donald] Trump's trade war is already triggering layoffs, killing jobs, and causing damage to future investment. U.S. tariffs threaten jobs across all sectors."
Ontario NDP Leader Marit Stiles will join Payne at the rally.