In a large bowl, whisk together the oil, milk, eggs, and sugar Add the flour and baking powder and stir until well combined.
Fold in the blueberries.
Spray the waffle iron with cooking spray. Fill the waffle iron with about 3/ cup of batter (this will vary depending on your maker) and cook until golden, about 2-3 minutes.
Carefully wipe off any blueberries that stuck to the iron before adding more batter for your next waffle.