In this work, the lithium-storage performance and mechanism of a designed (Ni0.5Co0.5)9S8@NC hollow nanocube composite as a rechargeable lithium-ion battery (LIB) anode are investigated. The nanocomposite is composed of a bimetallic sulfide (Ni0.5Co0.5)9S8 core and a surrounding nitrogen-doped carbon shell. It displays a superior electrochemical reactivity with an appealing specific capacity of 724 mAh g–1 at a specific current of 0.5 A g–1 cycled 80 times, as well as attractive stability and rate capability. The quantitative kinetic analysis reveals that the advanced lithium-storage performance is partly derived from the pseudocapacitive contributions. In situ X-ray diffraction (XRD) demonstrates the formation of Ni, Co, and Li2S in the conversion reaction during the initial cycling. Ex situ transmission electron microscopy (TEM) and scanning electron microscopy (SEM) demonstrate the volume expansion of the core (Ni0.5Co0.5)9S8 active material with the essential preservation of the complete (Ni0.5Co0.5)9S8@NC hollow nanocube structure during repeating cycling. Namely, the synergistic effect of the N-doped carbon coating, the rigid hollow nanostructure, and the multiple-electron-transfer conversion reaction of the bimetallic sulfide contributes to the superior lithium-storage performance of the nanocomposite.