Sometimes — with care
Plain, unsalted, shelled peanuts are safe for dogs in small amounts. Skip salted, flavoured or in-shell peanuts, and remember peanuts are high in fat.
Unlike some nuts, peanuts (which are technically legumes) are not toxic to dogs, and dry-roasted or raw unsalted peanuts make an okay occasional treat — it is the same plant behind dog-friendly peanut butter. The cautions are practical: peanuts are high in fat, so too many can upset the stomach or, over time, contribute to pancreatitis; salted and flavoured peanuts add too much sodium and seasoning; and shells are a choking and blockage hazard.
A few plain unsalted peanuts for a medium or large dog, occasionally. Skip them for small breeds and overweight dogs. Always shelled and unseasoned. If your dog has never had them, offer one and watch for any reaction — peanut allergies in dogs are rare but possible.
A little xylitol-free peanut butter gives the same flavour with less choking risk.
General information, not veterinary advice. If your pet has eaten something potentially harmful or shows symptoms, contact your vet or an emergency clinic immediately. Full disclaimer.