Wash and chop bell peppers, red onion, and carrots into bite-sized pieces. Mince the garlic and gather Italian seasoning, salt, and pepper.

Add chopped vegetables to the slow cooker, then layer minced garlic and Italian seasoning on top. Place boneless chicken thighs above, ensuring they are not overlapping.

Pour balsamic vinegar over the chicken and vegetables. Season with salt and pepper to taste.

Cover the slow cooker and cook on low for 6-8 hours, or on high for 3-4 hours. Check for doneness halfway through.

Once cooked, stir the mixture to combine flavors and serve hot.

Let leftovers cool before storing in an airtight container for up to 5 days. Can be frozen for up to 3 months.