Light-emitting diodes (LEDs) are incoherent light sources with limited bandwidths, and the discovery of biological effects of LED light sources promotes its application in biomedicine. Based on the phenomenon that tissue penetration depths of lights with different wavelengths are different, this work introduces the target tissue specificity and biological effects of LED light sources at each band. This article also reviews the current application of these LED light sources in a clinical setting for the treatment of dominant diseases. Finally, the application of LED light sources in the biomedical field is prospected herein to help guide their clinical application together with instrument research and development.