Supercapacitors have emerged as vital energy storage devices due to their high-power density, rapid charge–discharge capability, and excellent cycling stability, making them attractive for sustainable energy applications. Among advanced electrode materials, two-dimensional (2D) MXenes have gained significant attention because of their unique layered structure, high electrical conductivity, hydrophilicity, and tunable surface chemistry with abundant functional groups. However, their standalone performance is often limited by challenges such as restacking of nanosheets, susceptibility to oxidation, and relatively moderate capacitance, which restrict efficient ion transport and active surface utilization. This review provides a comprehensive overview of MXene materials, including their synthesis methods, surface engineering strategies, structural features, and electrochemical properties, with a particular focus on their integration into 2D/2D hybrid architectures with materials such as graphene, transition metal dichalcogenides, black phosphorus, boron nitride (BN/BCN), conductive polymers, and graphitic carbon nitride (g-C3N4). These hybrid systems effectively mitigate restacking, expand interlayer spacing, and enhance electrolyte accessibility, thereby improving ion diffusion and charge transport kinetics. Compared to conventional MXene-based composites such as 0D/2D and 1D/2D systems, 2D/2D hybrids offer larger interfacial contact, superior structural compatibility, and more efficient ion pathways, resulting in uniform charge distribution and enhanced mechanical durability during long-term cycling. Consequently, these architectures exhibit significantly improved specific capacitance, rate capability, and cycling stability. The review further highlights the fundamental charge storage mechanisms, including electric double-layer capacitance and pseudocapacitive behavior, along with the synergistic effects arising from interfacial interactions, and concludes by addressing current challenges and future perspectives toward scalable fabrication and practical implementation of 2D/2D MXene-based supercapacitors.