Slow-Roasted Prime Rib with Rosemary and Garlic

By Lauren Mitchell, Test Kitchen Director · Reviewed by AislePrompt Editorial · Published 2026-04-11 · Updated 2026-04-11

Slow-roasting at 250°F is the only technique that reliably produces an even medium-rare from the outer cap to the bone in a standing rib roast — high-heat methods drive a gradient (well-done crust, rare center) that the resting window can't fully reverse, while a low steady oven lets the interior temperature climb uniformly, leaving a consistent blush with no grey band. Pull the roast when the deepest point reads 120–125°F; carry-over cooking during the 20–30 minute rest will bring it to 130°F at the center. This is a holiday centerpiece and weekend project — plan on roughly 15 minutes per pound at 250°F, plus the rest — not a weeknight recipe. A bottle of Cabernet Sauvignon or Malbec pairs naturally with the rosemary-crusted beef fat. For more beef roast ideas or holiday dinner recipes, browse the full collection.

Ingredients

• 2.5 lbs bone-in prime rib roast
• 3 tbsp olive oil
• 4 cloves garlic
• 2 tbsp fresh rosemary
• 1 tsp salt
• 1/2 tsp black pepper

Instructions

1. Step 1: Pat the 2.5 lbs bone-in prime rib roast dry with paper towels, then rub 2 tbsp olive oil evenly over the surface. Season with 1 tsp salt and 1/2 tsp black pepper.
2. Step 2: Combine 4 minced garlic cloves, 2 tbsp chopped fresh rosemary, 1 tbsp olive oil, 1 tsp salt, and 1/4 tsp black pepper in a small bowl. Rub this mixture evenly over the entire roast.
3. Step 3: Place the roast on a rack in a roasting pan, fat side up, and insert a meat thermometer into the thickest part.
4. Step 4: Roast in a preheated 275°F oven for 2 hours 30 minutes, or until the thermometer reads 120°F for medium-rare.
5. Step 5: Remove from oven, tent loosely with aluminum foil, and let rest for 20 minutes before slicing.