Graphitic carbon nitrides (g-C N ) are a class of 2D polymeric materials mainly composed of carbon and nitrogen atoms. g-C N are attracting dramatically increasing interest in the areas of sensing, imaging, and therapy, due to their unique optical and electronic properties. Here, the luminescent properties (mainly includes photoluminescence and electrochemiluminescence), and catalytic and photoelectronic properties related to sensing and therapy applications of g-C N materials are reviewed. Furthermore, the fabrication and advantages of sensing, imaging and therapy systems based on g-C N materials are summarized. Finally, the future perspectives for developing the sensing, imaging and therapy applications of the g-C N materials are discussed.