Polymeric carbon nitrides (PCNs) have emerged as promising heterogeneous photocatalysts for organic transformations as they are metal-free, inexpensive, and possess suitable bandgaps, and excellent chemical- and photo-stability. However, current application of PCNs in organic synthesis is rather limited to several well-established materials, which limits the scope of reaction patterns and efficiency. We herein report the synthesis and fabrication of two new PCN nanosheets by incorporating nanostructure construction, element doping, and vacancy engineering into one hybrid platform. The heteroatom doped PCN nanosheets with vacancies feature highly porous structures with extremely large substrate-catalyst interface areas, enhanced charge separation, and improved lipophilicity. The generated heterogeneous catalysts demonstrate impressive photoredox catalytic performances in a variety of organic transformations (e.g., defluoroborylation, [2+2] cycloaddition, C-N, C-S, and C-O cross couplings), providing efficiencies comparable to reported optimized homogeneous catalysts and exceeding those with commonly utilized PCNs.