To establish the importance of surface chemistry of bulk single crystals in real practical fields, dimensionally/morphologically controlled nano-structured materials could act as a potential candidate. These are probably set up to bridge the gap between the quantum domain of 0D, 1D & 2D nano-materials and 3D macro-scale bulk materials. In order to overcome the intrinsic limitations of graphitic carbon nitride (g-C3N4), morphological/dimensional modification has been introduced since long. By varying the morphologies based on the quantum confinement effect, the physio-chemical as well as electronic properties of g-C3N4-based nano-structured photo-catalysts are found to be altogether different. The dimensional-dependent light absorption efficiency, surface area, availability of surface active sites, ease of transportation of exitrons, etc., are mainly accountable for the photo-catalytic performance of these nano-materials. Here, in this chapter, we have systematically summarized the various dimensionally/morphologically controlled g-C3N4-based materials with special reference to their designing process, photo-catalytic properties, and applications towards energy and environment.