Graphitic carbon nitrides (g‐C3N4) are a class of 2D polymeric materials mainly composed of carbon and nitrogen atoms. g‐C3N4 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‐C3N4 materials are reviewed. Furthermore, the fabrication and advantages of sensing, imaging and therapy systems based on g‐C3N4 materials are summarized. Finally, the future perspectives for developing the sensing, imaging and therapy applications of the g‐C3N4 materials are discussed. The sensing, imaging and therapy applications of g‐C3N4 materials are summarized. The luminescent, catalytic and photoelectronic properties and mechanisms of g‐C3N4 materials related to sensing and therapy applications are introduced and discussed. The principles and advantages of the sensing, imaging and therapy systems are concluded.