Preheat your oven to 350°F (175°C). Grease a 9x5-inch loaf pan or line it with parchment paper.
In a large mixing bowl, combine the mashed bananas and melted coconut oil. Mix until well combined.
Add the granulated sugar, beaten egg, and vanilla extract to the banana mixture. Stir until smooth.
In a separate bowl, whisk together the baking soda, salt, cinnamon, and flour.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix.
Gently fold in the blueberries until evenly distributed.
Pour the batter into the prepared loaf pan and smooth the top with a spatula.
Bake for 50-60 minutes, or until a toothpick inserted into the center comes out clean.
Let the bread cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely.