In a small bowl, mix together ¼ cup brown sugar, 2 tablespoons of chili powder, 1 tablespoon of smoked paprika, 1 tablespoon of onion powder, 1 tablespoon of garlic powder, 1 tablespoon of oregano, and 1 teaspoon of salt.
Generously cover the chicken with the rub. Make sure to press the rub into the chicken really well, especially under the skin. You want the chicken to be completely covered with the rub.
Cover the dish and refrigerate for 12-24 hours.
After the chicken has marinated, prep the smoker accordingly and preheat it until the smoker reaches 225°F.
Once the smoker has preheated, put the whole chicken on a rack in the smoker breast side up. Insert a meat thermometer into the side of the chicken breast ensuring it doesn't touch any part of the bone.
Smoke the chicken at about 225°F until the internal meat thermometer reaches 165°F.
When the chicken is done, remove it from the smoker.
Wrap it loosely with aluminum foil and let the chicken rest for 10 minutes before slicing and serving.