The development of advanced, cost-effective layered materials with high surface area and tunable, rich surface chemistry offers promising solutions for sustainable development. MXene and its nanocomposites have attracted considerable attention from academia and industry as multifunctional materials for energy harvesting and hydrogen evolution, owing to their unique performance characteristics. Due to its unique characteristics, including high electrical conductivity, hydrophilicity, tunable surface terminations, excellent mechanical properties, and structural flexibility, MXene has been widely used in energy storage, catalysis, electromagnetic shielding, and sensing applications. The key objective of the present research is to investigate recent advances in MXene-embedded nanocomposites for two critical applications: solar energy harvesting via photovoltaic systems and clean hydrogen production via photocatalytic water splitting into sustainable products. This research also highlights the mechanisms by which MXenes improve charge transport, suppress recombination, and enhance catalytic activity. Furthermore, this review highlights current challenges, including material oxidation, restacking, toxic synthesis routes, and interfacial incompatibility. Emerging trends such as green synthesis, quantum dot engineering, tandem solar-fuel systems, artificial intelligence (AI)–guided optimization, and flexible device integration, are also explored. By critically evaluating design strategies, limitations, and future directions, this review provides a foundational understanding of MXene-based materials for scalable, efficient, and sustainable solar energy and hydrogen production.