How to Grill a Leg of Lamb

For a butterflied leg of lamb, marinate for 4–24 hours in garlic, olive oil, rosemary, and lemon juice. Sear cut-side down over direct high heat for 5 minutes, flip, then finish over indirect heat until the internal temperature reaches 135°F for medium-rare. Rest 10–15 minutes before carving.

Butterflied vs. bone-in: which should you grill?

The most important choice is how the lamb is prepared before it hits the grill. Butterflied and bone-in behave differently in every way — cooking time, ease of carving, and how well they absorb a marinade.

For most home cooks, butterflied is the right choice. Ask your butcher to butterfly a bone-in leg, or buy a pre-butterflied leg — most grocery stores carry them in the 4–6 pound range. You can also do it yourself: remove the bone, open the leg flat, and pound any thick sections to more even thickness.

How to make the best lamb marinade

Lamb has a strong, distinctive flavor that pairs naturally with bold aromatics. The classic combination is garlic, fresh rosemary, lemon, and olive oil — the foundation every Mediterranean lamb dish is built on.

Simple garlic-herb marinade (for a 4–6 lb butterflied leg):

• 6 garlic cloves, minced
• 1/4 cup olive oil
• 3 tablespoons fresh lemon juice (about 1 large lemon)
• 2 tablespoons fresh rosemary, finely chopped
• 1 tablespoon fresh thyme leaves
• 2 teaspoons kosher salt
• 1 teaspoon black pepper
• 1/2 teaspoon red pepper flakes (optional)

Whisk together and pour over the lamb in a zip-lock bag or covered dish. Refrigerate for at least 4 hours, ideally overnight (12–24 hours). Turn the bag or flip the lamb at least once during marinating.

Variations to try:

• Greek-style: Add 2 teaspoons dried oregano and replace lemon juice with red wine vinegar
• Moroccan: Add 1 teaspoon each of cumin, coriander, and smoked paprika
• Mint-garlic: Replace rosemary with 3 tablespoons of fresh mint

Remove the lamb from the marinade 30–45 minutes before grilling. Pat the surface lightly dry — excess marinade on the surface can flare and burn before the crust develops.

What equipment do you need?

• Two-zone grill setup — direct searing heat on one side, indirect on the other. This is essential for controlling a large, irregular cut.
• Instant-read thermometer — the only reliable way to hit the right doneness. Uneven thickness across a butterflied leg makes time-only estimation unreliable.
• Long-handled tongs — to handle and maneuver the large cut safely over high heat.
• Basting brush — for applying extra olive oil or herb butter in the final minutes.

Recommended gear:

• Instant-read meat thermometer on Amazon — the Thermoworks Thermapen is the benchmark; the ThermoPop is the budget choice under $35
• Long-handled BBQ tongs on Amazon — at least 16 inches to keep your hands away from the heat

How to grill a leg of lamb: step-by-step

Step 1: Prepare the lamb. If the leg is not already butterflied, have your butcher do it or do it yourself. Trim excess surface fat, leaving about 1/4 inch — some fat adds flavor and bastes the meat as it renders, but thick fat deposits burn before the interior is done. Score the remaining fat cap in a shallow crosshatch pattern with a sharp knife, cutting about 1/4 inch deep and spacing the cuts about 1 inch apart. This helps the marinade penetrate and allows the fat to render more evenly on the grill.

Step 2: Marinate for 4–24 hours. Place the butterflied leg in a large zip-lock bag or a covered baking dish. Pour the marinade over it, making sure all surfaces are coated. Seal and refrigerate. For the best flavor, marinate overnight. Flip the lamb once or twice during marinating so all sides spend time submerged.

Step 3: Bring to room temperature. Remove the lamb from the refrigerator 30–45 minutes before grilling. Starting from cold extends total cooking time and can produce a wider grey band of overcooked meat under the crust. Pat the surface lightly with paper towels to remove excess marinade — wet surfaces steam rather than sear.

Step 4: Set up a two-zone grill. For gas: turn one or two burners to high, leave the others off. For charcoal: bank a full chimney of lit coals to one side, leaving the other side empty. Target 450–500°F on the direct zone and 325–350°F on the indirect zone. Preheat for 15 minutes with the lid closed. Clean and oil the grates just before cooking — brush them hot, then wipe with an oiled paper towel held in long tongs.

Step 5: Sear cut-side down over direct heat. Place the butterflied lamb cut-side down (the interior, rougher side) directly over high heat. Close the lid. Sear without moving for 4–5 minutes. Open the lid and check: the lamb should release cleanly with visible grill marks. If it sticks, wait another 60 seconds before checking again. Flip the lamb and sear the fat-side down for 4–5 minutes. Expect some flare-ups from fat dripping — keep the lid partially open or have a squirt bottle of water ready.

Step 6: Finish over indirect heat. After searing both sides, move the lamb to the indirect zone. Insert a thermometer probe into the thickest part of the leg, avoiding any remaining bone channel. Close the lid and cook until the thickest section reads 5°F below your target temperature (see the doneness guide below). A butterflied leg at 4–6 pounds typically takes 15–20 more minutes of indirect cooking after the initial sear. Check the thinner sections earlier — these will be more well-done and are ideal for guests who prefer that.

Step 7: Rest before carving. Transfer the lamb to a cutting board and tent loosely with foil. Rest for at least 10 minutes, preferably 15. The internal temperature continues to rise 5–8°F during resting. Do not skip this step — a leg of lamb cut immediately after grilling loses a significant amount of its juices onto the board.

Step 8: Carve and serve. Butterflied lamb does not have a single uniform grain direction, since the leg muscle is opened flat rather than cross-sectioned. Identify the main muscle groups and carve each one against its grain for maximum tenderness. Slice thin, about 1/4 inch, and arrange on a platter. Drizzle the accumulated resting juices over the top before serving.

Lamb doneness temperature guide

Always pull the lamb off the grill 5°F below your target — it will reach the final temperature during the rest.

Medium-rare (135°F final) is the widely recommended target for lamb. At this temperature the meat is pink, tender, and juicy, with the stronger flavors that some find off-putting mellowed by the heat. Medium (145°F) is a good starting point for those new to lamb who prefer less pink.

What to serve with grilled leg of lamb

Grilled lamb is rich and intensely flavored — sauces and sides that brighten or contrast work best.

Sauces:

• Mint chimichurri: Fresh mint, parsley, garlic, red wine vinegar, and olive oil blended in 5 minutes. Cuts the richness and adds a classic herbal lift.
• Tzatziki: Greek yogurt, cucumber, garlic, dill, and lemon. The classic pairing for Mediterranean-style lamb — cool and refreshing against the charred crust.
• Harissa: For the Moroccan-spiced variation, store-bought harissa paste adds heat and depth with no extra work.

Sides:

• Roasted vegetables on the grill — zucchini, bell peppers, eggplant — cooked in the final 20 minutes on the indirect zone while the lamb finishes
• Tabbouleh or couscous salad, cool and herby, balances the richness of the meat
• Grilled flatbread or pita, pressed directly on the hot grate for 60 seconds per side
• Simple arugula salad with lemon vinaigrette and shaved Parmesan

Common mistakes when grilling lamb

Not scoring the fat cap. A thick unscored fat cap renders unevenly and can cause sudden flare-ups as fat pockets liquify. A simple crosshatch pattern of shallow cuts, 1 inch apart, solves both problems and lets the marinade reach the meat underneath.

Skipping the marinade. Lamb benefits greatly from acid — lemon or vinegar — and bold aromatics to balance its natural flavor and tenderize the surface. A 4-hour minimum is needed for flavors to penetrate; overnight is noticeably better. Skipping this step leaves the lamb tasting more aggressively gamey.

Grilling bone-in like butterflied. A bone-in leg cannot be treated like a flat piece of meat. It is too thick for direct heat and needs an indirect roasting approach. Treating it like a butterflied leg results in a burnt exterior and raw center.

Cooking from cold. Lamb taken straight from the refrigerator to the grill takes longer to cook through and produces a wider grey band of overcooked meat under the crust. Letting it rest at room temperature for 30–45 minutes before grilling tightens the window between the crust and the pink center.

Cutting too early. A large cut like a leg of lamb holds significant residual heat and carries over more than a steak does. Cutting it immediately produces undercooked meat at the center and dry slices across the board. Resting for 10–15 minutes allows the temperature to equalize and the fibers to relax.

FAQ

Bottom line

Grilling a leg of lamb is more straightforward than it looks: butterfly the leg, marinate overnight in garlic, rosemary, and lemon, sear both sides over high direct heat, then finish over indirect heat to 135°F. A reliable thermometer and a 10-minute rest are the two things that separate a juicy, properly cooked leg of lamb from a dry, overcooked one. Start with a butterflied leg from your butcher, nail the temperatures, and it will be the centerpiece of any outdoor feast.

For related reading: how to grill lamb chops perfectly, how to grill a perfect steak with the same two-zone method, best grill thermometers for accurate readings, and gas vs. charcoal grill: which is right for you.