Combine the ground chicken, 1/4 cup of the buffalo wing sauce, breadcrumbs, egg, celery, onion, garlic powder, salt, and pepper in a large bowl. Mix until evenly blended.
Shape the mixture into a loaf that will fit inside your slow cooker.
Pour the remaining 1/4 cup buffalo wing sauce into the bottom of the slow cooker. Place the loaf on top.
Cover and cook on low for 6 hours until the internal temperature reaches 165°F.
Remove the meatloaf from the slow cooker and let it rest for 5 minutes.
Slice the meatloaf and drizzle ranch dressing over each serving.