Brown the Italian sausage in a skillet over medium heat, breaking it into small pieces as it cooks. Drain excess fat and transfer the sausage to the slow cooker.
Add the diced onion, sliced carrots, diced celery, and minced garlic to the slow cooker.
Stir in the drained white beans, diced tomatoes with their juice, chicken broth, and Italian seasoning.
Season with salt and black pepper, then cover and cook on low for 6 to 7 hours until the vegetables are tender.
Stir in the chopped parsley just before serving.