Light-mediated healthcare, including monitoring and therapy techniques, has evolved signifi cantly over the past decades,

owing to their advantages in minimal invasiveness and relatively low side eff ects. However, most of the clinically available

light sources have suff ered from their bulky size and rigidity, making them impractical for continuous on-body-type health

monitoring and treatment applications. Recently, wearable and implantable healthcare systems using deformable light

emitting diodes (LEDs) have been developed, which can be seamlessly integrated to any part of the body and exhibit the

potential to improve effi cacy of personalized and mobile photo-medicine. In this review, we discuss recent advances in

wearable and implantable LED technologies for various biomedical applications. First, we present an overview of the stateof-

the-art high-performance wearable and implantable LEDs, especially focusing on their light-emitting materials and

unique device design approaches. We also discuss strategies for integrated light-based healthcare systems. Then, we discuss

prominent examples of light-medicated sensing and therapeutic applications, whose accuracy and effi cacy can be enhanced

by wearable and implantable LEDs, ranging from non-invasive oxygen level sensing to various phototherapies. Finally, we

conclude this review with a brief outlook on the future technologies.