Add the shredded chicken, cream cheese, Greek yogurt, buffalo hot sauce, ranch dressing, garlic powder, and onion powder to the slow cooker. Stir until everything is well combined.
Cover and cook on low for 2 hours, stirring once if possible, until the mixture is hot and creamy.
After 2 hours, stir in the shredded mozzarella cheese. Cover and continue cooking for an additional 15–20 minutes, until the cheese is fully melted and the dip is smooth.
Give the dip a final stir and adjust seasoning or buffalo sauce to taste.
Garnish with blue cheese crumbles and sliced green onions just before serving. Serve warm directly from the crockpot with chips, crackers, bread, or fresh vegetables.