Abstract: A motorcycle helmet lock securely grasps a metal strap ring (or D ring) of a helmet strap to prevent helmet theft. The helmet lock includes a groove suitable to accept the strap ring and a locking bolt to advance through the strap ring to secure the helmet. The lock may be an integral part of a motorcycle grip or foot peg, may bolt to a common accessory attachment interface of known motorcycle grips, or include an expanding portion which expands inside a tubular handlebar end to attach the helmet lock. The lock may further be used on any type of vehicle using handlebars for foot pegs.