Preheat oven to 350 degrees F. Mist a muffin tin with nonstick cooking spray or line with muffin liners; set aside.
In a microwave-safe mixing bowl, melt the butter by microwaving on high for 30-45 seconds. Add the banana to the bowl and mash using the backside of a fork against the sides of the bowl. Add sugar, vanilla, eggs, and orange juice; whisk until well-combined.
In a separate bowl, whisk together 1¼ cups flour, baking soda, baking powder, and salt. Add to the wet ingredients and mix until just combined.
To the now empty bowl, add remaining ¼ cup flour and blueberries, gently tossing to coat. Gently fold the blueberries into the batter.
Using a ⅓ cup ice cream scoop, fill each muffin well two-thirds full. Bake for 25-30 minutes, until muffin tops are golden brown. Allow to cool before removing from pan.