In a large mixing bowl, combine the rolled oats, vanilla protein powder, dried blueberries, ground cinnamon, and ground flaxseed. Stir well to evenly distribute all dry ingredients.
Add the almond butter, honey, and vanilla extract to the dry ingredients. Mix thoroughly using a spatula or your hands until the mixture starts to come together.
Gradually add the unsweetened almond milk, one tablespoon at a time, mixing after each addition until the mixture is sticky enough to hold its shape but not too wet.
Using your hands, roll the mixture into 12 evenly sized balls, about 1 to 1.5 inches in diameter.
Place the protein balls on a baking sheet or plate lined with parchment paper.
Refrigerate the protein balls for at least 30 minutes to firm up before serving.