In a medium bowl, combine the 8 ounces room-temperature cream cheese and 3 tablespoons Buffalo hot sauce. Beat with a hand mixer on medium until smooth and well combined, scraping down the sides of the bowl with a spatula as needed.
Add 1/2 cup blue cheese crumbles, 1/3 cup diced celery, 1/4 cup thinly sliced green onion, 3 tablespoons diced red bell pepper, 2 tablespoons of the finely chopped walnuts, 1/2 teaspoon kosher salt, and 1/4 teaspoon black pepper. Stir with a spatula until evenly mixed. Taste and, if desired, add more Buffalo hot sauce, kosher salt, or black pepper; stir again to combine.
Lay a large piece of plastic wrap on your work surface. Spoon the mixture onto the center of the plastic wrap and use the wrap and your hands to form it into a smooth ball. Wrap tightly and refrigerate for about 1 hour to firm up.
Place the remaining finely chopped walnuts in a shallow bowl or dish. Unwrap the chilled cheese ball and roll it in the walnuts, pressing gently so the nuts adhere and the outside is fully covered.
Transfer the finished cheese ball to a serving plate and keep chilled until ready to serve. Serve with pita chips or crackers, celery sticks, and carrot sticks.