Conditioning the nature of metal active sites for better performance by well designing and constructing the support material is always appealing in heterogeneous catalysis. Herein, Cu species was introduced into the bulk phase of carbon nitride to strengthen the interlayer connection and optimize the electronic structure. The resulting material (CN-Cu) demonstrated an enhanced support effect for Pd catalyzed Suzuki cross-coupling reactions under light illumination. Detailed characterizations showed that Cu species were atomically incorporated in intra/interlayer of CN framework through coordinating with pyridinic nitrogen, leading to improved light absorption and more efficient charge carrier transfer. More importantly, the electronic effect of CN-Cu to the surface Pd was enhanced by the electron drift from Cu to N, thereby rendered an electron-rich Pd surface. Such Pd surfaces allowed faster electron injection from Pd(0) to the LUMO of aryl halides and therefore accelerate the rate-determining step of the coupling reaction.