Preheat the oven to 400°F. Line a sheet pan with parchment paper.
In a large bowl, combine all the meatball ingredients - ground turkey, bread crumbs, onion, celery, parsley, thyme, sage, salt, and black pepper - either by hand or with a food processor.
Shape the meatball mixture into 16 equally portioned meatballs. Place meatballs onto the lined baking sheet, spacing them out so that they are not touching.
Bake for 20 minutes, until the bottoms are golden brown and a meat thermometer shows an internal temperature of 165°F. Serve hot.