Smart wearable devices have become more and more popular in our daily life due to their unique power of “wearing-while-using.” However, requirements of light weight and compact size lead to limited on-device resources in most wearable products, which hamper the development of wearable technology. Edge computing provides an opportunity for wearable devices to access more resources without violating the constraints on weight and size. In this article, we first investigate the drawbacks of wearable devices and explore the potential of addressing such drawbacks by edge computing. Then we conduct a comprehensive survey on existing works from four aspects, i.e., computation scheduling, information perception, energy-saving, and security. Finally, we point out several future research directions worth our attention. We believe that wearable devices enhanced with edge computing technologies would bring more benefits and convenience to our life shortly.