Go Back
A nice thick slice of medium-rare prime rib on a plate with horseradish sauce.

Prime Rib in a Roaster Oven

Prime Rib in a Roaster Oven recipe provides an easy how-to for making prime rib roast in an electric roaster for the best-ever holiday meal.
Servings: 10 servings
Chef Alli
Print Recipe Pin Recipe
Prep Time 20 minutes
Cook Time 2 hours 30 minutes
Total Time 2 hours 50 minutes

Save this Recipe

Get the recipe emailed to you + sign up for all our latest!

Ingredients
 

  • 10 pound prime rib roast, about 5 ribs, bone rack removed and tied back on for roasting
  • 1 tablespoon seasoned salt
  • 1 tablespoon black pepper
  • 1 tablespoon onion powder or granulated onion
  • 1/2 cup unsalted butter softened
  • 3 large cloves garlic, minced or crushed

Instructions
 

  • Unwrap prime rib from packaging and pat dry with paper towels. Place the prime rib, fat side up, onto a large rimmed baking sheet.
    10 pound prime rib roast, about 5 ribs, bone rack removed and tied back on for roasting
  • Combine the seasoned salt with the black pepper and onion powder in a medium bowl, then add the softened butter and garlic, combining well until you have a smooth paste.
    1 tablespoon seasoned salt, 1 tablespoon black pepper, 1 tablespoon onion powder or granulated onion, 1/2 cup unsalted butter, 3 large cloves garlic, minced or crushed
  • Use your fingers to spread the seasoned garlic butter all over the prime rib roast, pressing it into all the nooks and crannies.
  • If there’s time, place the buttered roast into the fridge for 24 hours, uncovered, allowing it to season during this resting time.
  • When you are ready to cook the roast, remove it from refrigeration to let rest on the counter, uncovered, for at least 2 hours.
  • Preheat the electric roaster to 450 degrees F. (some roasters only go as high as 425 degrees F so use that), placing the rack into the bottom.
  • After 10-12 minutes, the roaster should be nicely preheated. Place the prepared prime rib roast onto the cooking rack.
  • Cover the roaster with the lid. Cook the prime rib roast on high (425-450°F) for 25-30 minutes or until the exterior of the beef is deep golden brown.
  • Reduce the roaster temperature to 350 degrees F., continuing to cook the prime rib for 10-12 minutes per pound, or until it reaches 125 degrees F. at the center, about 2 more hours. (This time will vary depending on how your electric roaster cooks.)
  • Remove the prime rib from the roaster and place it onto a large cutting board; cover the prime rib with foil and let it rest for rest for at least 15-30 minutes after you take it out from the roaster.

Notes

 

Recipe Tips 

If you want a really good exterior “crust” on your prime rib, do season it ahead and allow the roast to rest completely uncovered in the refrigerator for 24 hours. This allows the seasoning blend to penetrate the meat a bit, drawing out some moisture on the surface. As the prime rib cooks, it will get caramelized and crusty on the exterior, staying juicy and tender on the inside.
Cooking the prime rib roast in the electric roaster without liquid helps keep the exterior of the roast brown and caramelize. Adding liquid to the electric roaster makes the prime rib steam as it cooks. It will still be delicious, but won’t have the good “crusty” exterior that is desired when enjoying prime rib.
It’s recommended to cook prime rib roast just until it reaches rare or medium rare in doneness for the best eating experience. You can always cook slices of prime rib a little bit more, but once it’s overcooked, there’s no going back. So sad!
Make absolutely sure you give your prime rib roast some beauty rest before you cook. This allows the fat and meat juices that coagulate at the center of the meat to release some of their chill and the also give the protein fibers of the beef time to relax. The prime rib can then cook so much more evenly, providing the delicious eating experience we all long for.
Cooking times for this recipe will vary based on how your electric roaster oven cooks. As a general rule of thumb, a 12 lb. prime rib roast will take 12-14 minutes per lb. for medium-rare doneness.

Nutrition

Calories: 1199kcalCarbohydrates: 1gProtein: 52gFat: 108gSaturated Fat: 47gPolyunsaturated Fat: 4gMonounsaturated Fat: 46gTrans Fat: 0.3gCholesterol: 249mgSodium: 751mgPotassium: 853mgFiber: 0.2gSugar: 0.1gVitamin A: 239IUVitamin C: 0.4mgCalcium: 37mgIron: 5mg

Nutritional Disclaimer

Chef Alli is not a dietitian or nutritionist, and any nutritional information shared is an estimate.

Tried this recipe?Let us know how it was!