Photoelectrochemical (PEC) water splitting is a distinctive process for transforming sunlight into abundant green H2 and O2, effectively reducing carbon emissions to zero. This process holds the promise of mitigating existing global environmental and energy challenges. However, the slow rate of photon energy absorption and the low efficiency of separating and transferring photoinduced charge carrier pairs across the photoelectrode surface limit the PEC water-splitting activity, impeding its innovative application. Moreover, plasmon-induced PEC process signifies a capable advancement of PEC photoelectrodes. Specifically, layered double hydroxides (LDHs) are versatile photoelectrocatalysts extensively studied due to their layered structural features and exceptional physicochemical properties. Despite their significant potential in PEC water splitting, LDH materials often fall short due to limitations such as low conductivity, instability in acidic environments, and slow mass transfer. Optimal modification of LDH materials involves coupling with graphene support and/or incorporating plasmonic nanoparticles to augment the light-harvesting capability of the materials and introduce new physicochemical characteristics. This modification facilitates effective charge separation and transportation while establishing coherence between the structure, properties, and activity of the resulting hybrid system. This book chapter provides a clear explanation of the fundamental principles underlying PEC water splitting and explores various mechanistic features responsible for plasmon-enhanced PEC water-splitting processes and advancements. Consequently, this chapter also presented the recently updated strategies for coupling LDH-graphene and related plasmonic LDH-graphene hybrid materials to enhance PEC water-splitting performances. Finally, we summarized the necessity for future research direction using LDH-graphene and plasmonic-based LDH-graphene hybrid to advance PEC water splitting, conducive to the establishment of a sustainable future. Additionally, we reviewed the latest characterization techniques, from structural analysis to the identification of reaction measures, with various strategies for photoelectrode fabrication, correlating intrinsic structural features with catalytic activities.