Place the room-temp cream cheese and Buffalo sauce in a medium bowl. Beat with a hand mixer until well combined and smooth.
Add blue cheese, celery, green onion, red bell pepper, 2 tablespoons of the walnuts, salt, and pepper to the bowl and stir to combine with a spatula. Taste and add more Buffalo sauce, salt, and/or pepper if desired.
Turn the mixture out onto a large piece of plastic wrap. Wrap and form into a ball shape with your hands. Place in the refrigerator for about 1 hour to firm up.
Place the remaining walnuts in a shallow bowl or dish. Unwrap the cheese ball and roll in the nuts until the outside is fully covered. Serve or keep chilled in refrigerator until serving. Serve with pita chips, crackers, celery sticks, and/or carrot sticks.