Sulfur is a promising cathode material with a high theoretical capacity of 1672 mAh g−1, but the challenges of the low electrical conductivity of sulfur and the high solubility of polysulfide intermediates still hinder its practical application. In this work, we design and synthesize a special carbon black nanoparticle–sulfur composite cathode material (NCB-S@NCB) with a novel structure and a high sulfur content of 84 wt% for lithium–sulfur battery application. The NCB-S@NCB composite cathode delivers a high initial discharge capacity of 1258 mAh g−1 and still maintains a reversible capacity of 865 mAh g−1 after 100 cycles with a relatively constant Coulombic efficiency around 98.0%.