Preheat your Traeger grill to 225°F (107°C) using wood pellets of your choice (such as oak or hickory) for a smoky flavor.
Remove the prime rib from the refrigerator and let it sit at room temperature for about 1-2 hours.
Season the prime rib generously with kosher salt and freshly ground black pepper. Optionally, you can apply a dry rub or seasoning blend to enhance the flavors further. Ensure all sides of the roast are coated.
Place the prime rib, fat side up, directly on the grill grates. Carefully insert a meat thermometer into the thickest part of the meat, ensuring that it does not come into touch with the bone.
Close the lid of the Traeger grill and let the prime rib slow-cook for approximately 3-4 hours, or until the internal temperature reaches your desired level of doneness.
Once the prime rib reaches the desired temperature, remove it from the grill and tent it loosely with aluminum foil. Allow the juices to redistribute by letting it to rest for 15-20 minutes.
After resting, carefully slice the prime rib across the grain into thick, juicy slices.
Serve immediately and enjoy!