Place the chicken breasts in the bottom of the slow cooker.
Add the cannellini beans, carrots, celery, onion, and garlic on top of the chicken.
Pour the chicken broth over the ingredients.
Sprinkle in the rosemary, thyme, oregano, salt, and black pepper.
Cover and cook on low for 6 hours.
Remove the chicken, shred it with two forks, and return it to the slow cooker.
Stir in the fresh spinach and let it cook for 10 more minutes until wilted.