Mash the banana in a large mixing bowl until mostly smooth with minimal lumps remaining.
Stir in the rolled oats and ground cinnamon until evenly combined and a firm dough forms.
Scoop into 6 equal small bite-sized balls using a tablespoon or cookie scoop.
Chill in the refrigerator for at least 30 minutes to firm up before serving.
Storage & Make-Ahead Tips: Store in an airtight container in the refrigerator for up to 5 days, or freeze on a parchment-lined baking sheet and transfer to a freezer bag for up to 3 months.