Remove the chicken from the refrigerator and pat it thoroughly dry with paper towels.

Place the chicken on a parchment-lined baking sheet or similar surface for easy transport to the smoker. Brush both sides of the chicken with olive oil.

In a small bowl, combine the kosher salt, smoked paprika, brown sugar, garlic powder, black pepper, onion powder, cayenne, and celery salt to create the rub.

Generously sprinkle the dry rub all over the chicken and let it sit at room temperature while you prepare the smoker.

Preheat your smoker to 225 degrees Fahrenheit. If using a charcoal smoker, the fire doesn't need to be large. Add wood chips or chunks to the charcoal before lighting. It's okay if the smoker temperature exceeds 225 degrees slightly, but be mindful as it may cook the chicken faster.

Brush the smoker grates with canola oil to prevent sticking, then place the chicken breasts on the grates.

Smoke the chicken until it reaches an internal temperature of 160 degrees Fahrenheit, which typically takes 45 to 60 minutes depending on breast size, smoker temperature fluctuations, and setup. Check progress after 30 minutes and monitor the internal temperature rather than relying solely on time.

If using butter, melt it in a small bowl and baste the chicken once it reaches 140 to 150 degrees Fahrenheit, around 30 minutes into cooking, to enhance tenderness and flavor.

Continue smoking until the chicken reaches 160 degrees Fahrenheit, approximately 15 more minutes.

Remove the chicken from the smoker, tent it loosely with foil, and let it rest for 5 minutes.

Slice the chicken and serve. Enjoy your smoked chicken!