Photocatalysis is a green technology and has received increasing attention owing to its potential in solving environmental problems in a sustainable manner. Among the candidates of semiconductor photocatalysts, graphitic carbon nitride (g-C3N4) stands out for environmental purification because of its elemental abundances, structure robustness, and high performances. In this paper, we present a mini review of sustainable photocatalytic remediation of micropollutants over morphology-engineered g-C3N4. The methods for advanced morphology control of g-C3N4 are discussed and insights into morphology-dependent photocatalysis over g-C3N4 are unveiled. The review also provides perspectives of challenges and solutions to sustainable water purification over the metal-free polymer materials.