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Slow Cooker Prime Rib
4.4 from 58 votes

Slow Cooker Prime Rib

Slow Cooker Prime Rib is a richly flavored roast cooked gently in a crock pot to retain moisture and tenderness. The rib roast is seasoned with salt, black pepper, and dried thyme, seared to form a caramelized crust, and slow-cooked atop aromatic onions, bay leaves, and rosemary. The pan juices with red wine and beef broth create a base for a savory gravy thickened with xanthan gum, mustard, and Worcestershire sauce. This method yields a tender roast with a balanced herbal aroma and a robust gravy ideal for a comforting meal.

Prep Time
20 mins
Cook Time
3 hrs
Additional Time
30 mins
Total Time
3 hrs 50 mins
Servings: 6 - 8
Calories: 1266 kcal
Course: Main Course
Cuisine: American

Ingredients

For the roast
  • 5 ½ pounds standing rib roast 2 ½ kg
  • salt
  • black pepper
  • 2 tsp dried thyme or mixed herbs
  • 2 tbsp vegetable oil
  • 1 onion , sliced into rounds
  • ⅓ cup red wine for deglazing the pan, 80ml
  • 2 bay leaf
  • 1 rosemary fresh sprig
  • 1 cup beef broth or stock from a stock cube
For the gravy
  • 1 tsp xanthan gum or see notes
  • 1 tbsp Worcestershire sauce or soy sauce
  • 2 tsp mustard
  • salt to taste
  • black pepper to taste

Instructions

Prepare the joint
    Cup of Yum
  1. Allow the beef to come to room temperature for 30 minutes or up to an hour for a large joint.
  2. Slice the fat on top of the joint on the diagonal to create a diamond pattern (unless already prepared). Season the beef library with several turns of the salt and pepper mill on all sides and sprinkle with dried thyme. Allow the beef to come to room temperature for 30 minutes or so.
  3. Heat the oil in a large skillet and sear the beef over high heat on all sides, using tongs to turn it. Set aside.
  4. Add the sliced onion to the hot pan and pan fry until colored. Set aside.
  5. Deglaze the hot pan with a generous slug of red wine (or you can use Marsala) and cook for a couple of minutes until reduced. Use a wooden spoon to scrape any browned bits loose (all the yummy flavor hides in these!).
  6. Pour the pan juices into the slow cooker. Add the onion, bay leaves and rosemary. Place the rib joint in the crock pot resting it on the bones with the skin side uppermost. Pour in the beef broth.
  7. Cover and cook for approximately 3-3 ½ hours on LOW or until the desired temperature is reached on an instant read thermometer (see notes for a guide). Check the temperature after 3 hours or sooner if you use a smaller joint than the one specified.
  8. Rest the beef for 20-30 minutes or longer, loosely covered with foil while you prepare the gravy.
Make the gravy
  1. Strain the cooking liquid from the slow cooker into a saucepan. Stir in Worcestershire sauce, mustard and the xanthan gum (or cornstarch slurry). Bring to a simmer, cooking until the gravy thickens. Check the seasoning and adjust if needed.
Slice and serve
  1. Remove any string from the joint. Position a sharp knife between the ribs and meat and slice pushing against the bones to release the meat from the ribs.
  2. Slice the meat thinly across the grain and serve with the gravy and your choice of sides.

Notes

  • Use a meat thermometer inserted into the thickest part of the rib roast, avoiding bones, to check doneness accurately.
  • Allow the roast to rest after cooking, as its internal temperature will rise about 3-4°C (5-7°F) during this time.
  • You can thicken the gravy using cornstarch dissolved in cold water instead of xanthan gum if preferred.
  • Deglazing the searing pan with red wine captures flavorful browned bits, intensifying the gravy's taste.

Nutrition Information

Calories 1266kcal (63%) Carbohydrates 3g (1%) Protein 57g (114%) Fat 111g (171%) Saturated Fat 46g (230%) Polyunsaturated Fat 4g (24%) Monounsaturated Fat 48g (240%) Cholesterol 251mg (84%) Sodium 396mg (17%) Potassium 994mg (21%) Fiber 1g (4%) Sugar 1g (2%) Vitamin A 6IU (0%) Vitamin C 2mg (2%) Calcium 42mg (4%) Iron 6mg (33%)

Nutrition Facts

Serving: 6 - 8

Amount Per Serving

Calories 1266

% Daily Value*

Calories 1266kcal 63%
Carbohydrates 3g 1%
Protein 57g 114%
Fat 111g 171%
Saturated Fat 46g 230%
Polyunsaturated Fat 4g 24%
Monounsaturated Fat 48g 240%
Cholesterol 251mg 84%
Sodium 396mg 17%
Potassium 994mg 21%
Fiber 1g 4%
Sugar 1g 2%
Vitamin A 6IU 0%
Vitamin C 2mg 2%
Calcium 42mg 4%
Iron 6mg 33%

* Percent Daily Values are based on a 2,000 calorie diet.