In a large bowl, combine the flour, granulated sugar, baking powder, baking soda, salt, and cinnamon. Mix well to combine.
In another bowl, whisk together the egg, milk, and vanilla extract until smooth.
Pour the wet ingredients into the dry ingredients and stir until just combined. Gently fold in the blueberries, being careful not to crush them.
Heat about 2 inches of vegetable oil in a deep skillet or pot over medium heat until it reaches 350°F.
Using a spoon or small ice cream scoop, drop spoonfuls of the batter into the hot oil, making sure not to overcrowd the pan. Fry for about 2-3 minutes on each side or until golden brown.
Remove the fritters with a slotted spoon and drain on paper towels.
Dust the warm fritters with powdered sugar before serving.