Preheat oven to 350F. Grease and flour a 9×5-inch loaf pan.
In a medium bowl, whisk together flour, baking powder and salt.
In a large bowl, whisk together sugar, vegetable oil, egg, vanilla and mashed bananas until smooth. Add in flour mixture and stir until just combined and no streaks of flour remain. Fold in blueberries with a spoon or spatula, then pour batter into prepared pan.
Bake for about 55-60 minutes, until a toothpick inserted into the center of the loaf comes out with only a few moist crumbs attached.
Let bread cool in pan for 10 minutes, then turn out onto a wire rack to cool completely before slicing.