Water splitting technology is rapidly evolving in order to generate H2 in a sustainable manner to amendthe global energy crisis. Water splitting over semiconductor catalyst nanoparticles for large-scale hydrogenproduction has shown to be a simple and affordable procedure, attracting researchers from aroundthe world for more fruitful studies and development in the field of photocatalysis. In this respect,MoSe2 is a promising semiconductor photocatalyst owing to its non-toxic nature, low Gibbs free energy,high metallic character, impressive opto-electronic properties, and outstanding photocatalytic performance. Moreover, the 2D nature of MoSe2 allows the easy tuning of the bandgap to suit H2 evolution reactionapplication by simple synthesis techniques. Therefore, in this review, we have comprehensivelydiscussed the influence of morphology on photocatalytic water splitting with a main focus on the nanostructuremodifications to modulate the properties of MoSe2. In detail, starting from the crystal structureand optimal photocatalytic features of MoSe2, insights into photocatalytic water splitting have been highlighted. Various modes of nanostructure designs involving hydro(solvo)thermal, CVD, PVD, exfoliation,and intercalation are outlined. The lower bandgap energy is subjected to a high rate of photoinducedexcitons recombination, which reduces its photocatalytic efficiency. Therefore, modification techniquessuch as doping, heterostructure construction, and vacancy generation are presented in order to concurrentlyimprove the photocatalytic water splitting performance. Finally, the study concludes with a summaryof recent advancements and anticipated potential trends in this area to instigate further researchendeavours.