Room-temperature sodium–sulfur (RT Na–S) batteries are attractive low-cost energy-storage systems but remain limited by severe polysulfide shuttling, sluggish redox kinetics, and poor cycling stability. Herein, a multifunctional Mo@Si@S composite cathode is developed to regulate polysulfide chemistry and enhance electrochemical performance. The synergistic integration of polar, catalytically active MoS2 and mechanically robust SiC suppresses Na2Sx dissolution, improves charge-transfer kinetics, and promotes diffusion-controlled Na+ transport. The Na‖NaPF6‖Mo@Si@S cell delivers a high initial discharge capacity of ∼1400 mAh g−1 at room temperature and exhibits improved cycling stability after short-term ambient storage, indicating favorable electrode–electrolyte interfacial evolution. Nevertheless, pronounced capacity decay during the early cycles and limited long-term capacity retention reveal persistent challenges related to sulfur utilization and interfacial degradation. These results demonstrate both the promise and the remaining limitations of MoS2–SiC-based cathodes and provide guidance for further optimization toward durable RT Na–S batteries.