<p>Graphitic carbon nitride (g-C₃N₄) has emerged as a promising visible-light-responsive photocatalyst for environmental remediation, owing to its suitable band gap, chemical stability, and tunable structure. This review critically examines the structural properties, synthesis strategies, and pollutant degradation capabilities of g-C₃N₄. It is typically synthesized via thermal polymerization of nitrogen-rich precursors such as melamine or urea, though advanced methods like chemical vapor deposition, microwave-assisted, and template-based techniques offer greater control over morphology, porosity, and optical properties. Characterization tools including XRD, FTIR, SEM, TEM, BET, and UV–Vis spectroscopy are essential in understanding the material’s structure–performance relationship. The photocatalytic mechanism of g-C₃N₄ involves light absorption, charge carrier generation, and the formation of reactive oxygen species that oxidize and decompose various pollutants. g-C₃N₄ has shown significant efficiency in degrading dyes, antibiotics, and pesticides, contributing to cleaner water systems and safer environments. This review also highlights current challenges such as charge recombination and limited surface area, and discusses future directions for enhancing photocatalytic performance through material modification and hybrid system design.</p> Graphical Abstract <p></p>