Lithium-ion batteries are widely used owing to their advantageous performance characteristics. However, safety issues associated with liquid electrolytes have inspired the development of all-solid-state lithium−sulfur (Li/S) batteries as safe and high-energy-density candidates for next-generation batteries. Lithium sulfide (Li 2 S)-based positive electrode materials exhibit a high charge−discharge capacity and cycle performance. However, because of their insulating nature, ionic and electronic conduction pathways must be created for charge−discharge cycling. In this study, the incorporation of lithium sulfite (Li 2 SO 3 ) to create nanoscale lithium ionic pathways in Li 2 S-based positive electrodes was investigated. Li 2 SO 3 was synthesized and electrochemically characterized for the first time. Li 2 S− Li 2 SO 3 samples were prepared via ball-milling, and the composite positive electrodes combined with conductive additives were utilized as positive electrodes in all-solid-state batteries. The cells with Li 2 SO 3 exhibited a high reversible capacity, excellent rate performance (1C rate), and a long cycle life (1000 cycles). Li 2 SO 3 will be useful not only for Li 2 S-based positive electrodes but also for the development of materials for all-solid-state batteries.