Add drained chicken, cream cheese, Colby Jack cheese, Buffalo sauce, and ranch dressing into the slow cooker.
Stir everything together until well combined.
Cook on low for 1-2 hours, stirring occasionally, until fully melted and creamy.
If using the stovetop, heat over medium-low, stirring until smooth and warm (about 15-20 minutes).
Taste and adjust the spice level by adding more Buffalo sauce if needed.
Serve hot with tortilla chips, celery sticks, or carrots.
Garnish with extra shredded cheese or green onions for added flavor.
Enjoy immediately or keep on the "warm" setting in the slow cooker for serving.