Prime rib has a reputation for being difficult. It's not. It's just expensive, which makes people nervous (understandably!). This Slow Cooker Prime Rib Roast takes the pressure completely off: seared to build a crust, slow-cooked in a garlic herb compound butter, and brought to a perfect finish without you hovering over anything. The compound butter alone is reason enough to make this: a full head of garlic, fresh thyme, Dijon, and horseradish worked into a whole stick of softened butter and slathered all over the beef. The result is incredibly tender, juicy, perfectly medium-rare prime rib with a bold, garlicky herb crust, all with minimal hands-on time and zero oven-babysitting.
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Slow Roasted Prime Rib, Stress Free Every Holiday (Crock Pot Method) 🥩
We cook for a living. Which means that by the time the holidays roll around, the last thing we want to do is spend four hours hovering over the oven, thermometer in hand, trying not to ruin a $150 roast in front of company. Oven-roasted prime rib demands a level of attention that's hard to maintain when you're also making sides, setting the table, and trying to have a conversation. The slow cooker is our answer to that.
Cooking prime rib low and slow gives you the most evenly cooked, juicy result you can get at home. The temperature is controlled, the margin for error is essentially zero, and you get your holiday back. Dinner handles itself.
The process is straightforward: season and dry brine overnight, sear to build the crust, slather the whole thing in garlic herb compound butter, then let the crockpot do its thing for a few hours. And if you end up with leftovers (lucky you!), our prime rib sandwich with caramelized onions & arugula is waiting. 😉
🥩 Ingredients for This Slow Cooker Prime Rib Roast
This recipe relies on a handful of pantry staples to build bold flavor on a beautiful cut of beef. The compound butter is where TONS of flavor comes from, don't skip it!
How to Make Slow Roasted Prime Rib in the Crockpot ✨
Don't let the fancy reputation fool you - this comes together in a few straightforward steps. The sear does the heavy lifting up front; the slow cooker takes it from there.
- Step 1: Season the roast generously on all sides with kosher salt and black pepper. If you have the time, set it uncovered in the fridge for 24 hours. This dry brine lets the seasoning penetrate the meat and crisps up the fat cap beautifully.
🧂 A note on salt: This recipe is made with Diamond Crystal kosher salt, and we use about 1 teaspoon per pound of meat. If using Morton's or table salt, use about half the amount; they're significantly saltier by volume.
💡 Short on time? If you can't dry brine overnight, season at least an hour before cooking, and let the roast come to room temperature before searing. This promotes a more even cook.
- Step 2: Heat a large skillet over medium-high heat and add oil. Sear the roast for about 4 minutes on the rib side, then 2-3 minutes on each remaining side until deeply browned all over. Hold it upright with tongs for the sides if needed.
🔥 Don't skip the sear. The slow cooker can't produce the Maillard browning that makes prime rib taste so delicious. Two minutes per side in a hot pan is what gives you that caramelized crust, the slow cooker keeps it tender, and the combo of both is what really makes this roast the best!
- Step 3: While the roast rests briefly after searing, add the softened butter, minced garlic, fresh thyme, horseradish, and Dijon together in a bowl.
Mix until it forms a thick, fragrant paste. Season with a bit more salt and pepper.
🧈 The compound butter is the flavor engine of this recipe. A whole head of garlic and a full stick of butter sounds like a lot - it is, and that's the point. It melts into the meat over the long, slow cook and produces the most incredible drippings.
- Step 4: Spread the compound butter generously over the top and sides of the seared roast. No need to put it on the bottom.
Add the beef stock and thyme sprigs to the slow cooker, then place the roast in the slow cooker, rib side down.
💡 Bone-in vs. boneless: Both work great here. Bone-in (standing rib roast) adds a touch more flavor from the marrow and makes for a more impressive table presentation. Boneless is easier to slice and fits better in smaller slow cookers. Either way, go by temperature - not time.
🕐 How long to cook prime rib in the crock pot (on LOW):
- 4-5 lb roast: approximately 3-4 hours
- 5-6 lb roast: approximately 3.5-4.5 hours
- 6-8 lb roast: approximately 4.5-5.5 hours
These are estimates - every slow cooker runs differently, and roast shape affects cook time as much as weight. Always use a meat thermometer. Don't lift the lid to check early; each peek adds 15-20 minutes.
A meat thermometer is non-negotiable on a roast this expensive. Don't guess.
❄️ Temperature guide (pull at 5-8°F below target - the roast will continue to rise as it rests):
- Rare: pull at ~120°F (finished ~125-127°F)
- Medium-rare: pull at ~125-130°F (finished ~130-135°F) ← our recommendation
- Medium: pull at ~135°F (finished ~140-145°F)
Rest before slicing. Transfer to a cutting board, tent loosely with foil, and let rest for 20-30 minutes. This is non-negotiable - it allows the juices to redistribute so every slice is nice and juicy.
- Step 5: Use a sharp carving knife and slice against the grain. For a bone-in roast, run the knife along the bones first to free them, then slice.
Serve sliced thick with the pan drippings spooned over the top, and a generous spoonful of creamy horseradish sauce on the side. It's a classic pairing for a reason, and making it homemade takes about five minutes.
This is the kind of meal that feels like a restaurant experience without requiring you to leave your house, and the slow cooker method means you can actually enjoy the event instead of sweating in the kitchen. 🤤
✨ Want a crispier fat cap? Before resting, transfer the roast to a foil-lined baking sheet and broil on high for 3-5 minutes. Watch it closely - the fat cap can go from golden to burnt fast.
What to Serve With Slow Cooker Prime Rib Roast 🍽️
Whether it's Thanksgiving, Christmas, Easter, or any other occasion, the sides are almost just as important as the roast.
Our homemade creamed spinach is perfect. It's rich, garlicky, and deeply savory in a way that belongs on the same plate as prime rib. If you want something heartier, our truffle mashed potatoes or duck fat fondant potatoes are both worthy of a centerpiece roast. For something sweet, try this sweet potato casserole with brown sugar pecans; it rounds out the savory richness beautifully.
And if you're feeding a crowd and want to go all out, our honey pineapple-glazed ham is just as hands-off as this roast. It goes in the oven while the prime rib finishes in the slow cooker. Two impressive centerpieces with minimal extra stress. 😉
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📖 Recipe
Slow Cooker Prime Rib Roast (Tender, Juicy & Foolproof)
Equipment
- large slow cooker
Ingredients
For the roast:
- 5 pound prime rib roast bone-in or boneless; also called beef ribeye roast or standing rib roast
- 5 teaspoons kosher salt 1 teaspoon Diamond Crystal per pound, see notes
- 1½-2 teaspoons coarse ground black pepper
- 1-2 tablespoons neutral oil as needed to seare
For the compound butter:
- ½ cup unsalted butter softened (1 stick)
- 10-12 cloves garlic minced (1 whole head)
- 1 tablespoon fresh thyme minced
- 1 tablespoon prepared horseradish
- 1 tablespoon Dijon mustard
- kosher salt & black pepper to taste
For the slow cooker base:
- 1 cup beef stock
- 6-8 sprigs fresh thyme
Instructions
Season and dry brine:
- Season the roast generously on all sides with kosher salt and coarse ground black pepper. For best results, place uncovered on a rack in the refrigerator for 12-14 hours. If short on time, season at least 1 hour before cooking and let come to room temperature.5 pound prime rib roast, 5 teaspoons kosher salt, 1½-2 teaspoons coarse ground black pepper
Sear:
- Heat a large skillet over medium-high heat and add oil. Sear the roast for about 4 minutes on the rib side, then 2-3 minutes on each remaining side until deeply browned all over. Remove from the skillet and set aside.1-2 tablespoons neutral oil
Make the compound butter:
- In a medium bowl, combine the softened butter, minced garlic, fresh thyme, horseradish, and dijon mustard with a pinch of salt and pepper. Mix well until a thick paste forms. Spread over the top and sides of the seared roast (not the bottom).½ cup unsalted butter, 10-12 cloves garlic, 1 tablespoon fresh thyme, 1 tablespoon prepared horseradish, 1 tablespoon Dijon mustard
Slow cook:
- Add the beef stock and thyme sprigs to the slow cooker. Place the roast ribs-side down. Cover and cook on LOW for 3-5 hours, until an instant-read thermometer inserted in the thickest part reads 5-8°F below your target doneness (see Notes for temperature guide).1 cup beef stock, 6-8 sprigs fresh thyme
Rest and serve:
- Transfer to a cutting board, tent loosely with foil, and rest for 20-30 minutes before slicing. Spoon drippings from the slow cooker over the slices to serve.
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Notes
- Optional broil finish: For a crispier fat cap, transfer the roast directly from the slow cooker to a foil-lined baking sheet and broil on high for 3-5 minutes before resting. Watch closely - it can go from golden to burnt quickly. Rest as directed after broiling.
- Temperature guide (pull 5-8°F below target - roast continues to rise while resting):
-
- Rare: pull at ~120°F (finished ~125-127°F)
- Medium-rare: pull at ~125-130°F (finished ~130-135°F) - recommended
- Medium: pull at ~135°F (finished ~140-145°F)
- Well-done: not recommended for prime rib
- Cook time guide (on LOW):
-
- 4-5 lb roast: approximately 3-4 hours
- 5-6 lb roast: approximately 3.5-4.5 hours
- 6-8 lb roast: approximately 4.5-5.5 hours All slow cookers run differently - always verify with a thermometer. Don't lift the lid early.
- Salt note: Recipe is written for Diamond Crystal kosher salt. If using Morton's kosher salt, use approximately half the amount by volume.
- Make-ahead: Season the roast up to 24 hours in advance and dry brine uncovered in the refrigerator. The compound butter can also be made up to 24 hours ahead and stored covered in the fridge - bring to room temperature before slathering.
- Storage: Store leftover prime rib slices in an airtight container in the refrigerator for up to 4 days.
- Reheating: Reheat gently in a 275°F oven, loosely covered with foil, until warmed through. Avoid the microwave - it overcooks the edges quickly.
- Freezing: Freeze sliced leftover prime rib in an airtight freezer-safe container for up to 3 months. Thaw overnight in the refrigerator before reheating.
- Serving suggestions: Pairs beautifully with creamy horseradish sauce, steakhouse creamed spinach, and old fashioned sweet potato casserole. For leftovers, try our prime rib sandwich with caramelized onions & arugula.
mk says
So how long should it take to cook a 12lb. bone in prime rib in a crock pot. I purchased a 10 quart capacity crock pot. Rib fits perfectly , just don't know how long to cook.
Briana says
Hi there!
We're thinking that since your roast is about twice as big as the one we made, it should take roughly twice as long to cook. We like our roast to be medium-rare, and it took about 3 hours and 15 minutes. For a 12-pound roast it could take anywhere from 6 hours - 9 hours. We can't say for sure, that's why we have to insist on using monitoring it with a meat thermometer so you don't over or undercook it!
Happy New Year!