How to Reheat Crab Legs? To reheat crab legs, start by thawing them if frozen. Steam or boil the crab legs for 4-5 minutes until heated thoroughly. Alternatively, wrap them in foil and bake in the oven at 350°F for 10-12 minutes. Serve with melted butter and enjoy the succulent flavors of reheated crab legs for a delightful culinary experience.