Preheat your oven to 450°F (232°C).
Season the prime rib roast with kosher salt, black pepper, garlic powder, and rosemary.
Place the roast in a roasting pan showing the fat side up.
Roast in the preheated oven for 20 minutes, then reduce the temperature to 325°F (163°C).
Continue roasting until the internal temperature reaches your desired doneness.
Remove from the oven and let it rest for at least 20 minutes before slicing.
