Two-dimensional (2D) materials have great potential in macromolecular synthesis, yet there are some areas that still need to be explored, such as anionic polymerization. In this study, we present the first example of photoinduced anionic polymerization of ethyl-2-cyanoacrylate (ECA) using 2D graphitic carbon nitride (g-C3N4) as an active photocatalyst responsive to visible light. Our results demonstrate that particularly the mesoporous structure of g-C3N4 can initiate polymerization through the generation of electron-hole pairs upon exposure to visible light. To have a better insight into mechanistic pathways, several experiments, including control experiments, are conducted. The obtained polymers and the synthesized g-C3N4 materials are characterized comprehensively by chromatographic, thermal, and spectroscopic techniques. Accordingly, this study demonstrates an innovative process that can offer several advantages over traditional polymerization methods, including the ability to initiate polymerization at ambient temperatures and achieve high polymerization rates.@en