Brining whole chicken is a great flavor booster and insurance policy that you’ll end up with super moist birds after a long slow smoking. If you want to make two chickens just double the brine.
For the brine, bring water to a boil in a large saucepan. Add the salt, honey, rosemary, peppercorns, and garlic, stirring to dissolve the salt. Remove from the heat and add the ice cubes to cool the brine quickly to room temperature.
Place the chicken in a jumbo resealable plastic bag or large bowl. Pour brine over chicken; seal the bag or cover and refrigerate for 2 to 4 hours.
Heat smoker according to manufacturer’s directions. Remove the chicken from the brine; dry off. Lightly rub with oil and sprinkle with a seasoning rub if desired; place on smoker rack. Cover and cook about 4 hours or until no longer pink near the bone and juices run clear (165˚F internal temperature on an instant read thermometer near the thigh bone.)