Commercialization of the lithium‐sulfur battery is hampered by bottlenecks like low sulfur loading, high cathode porosity, uncontrollable Li2Sx deposition and sluggish kinetics of Li2S activation. Herein, we developed a densely stacked redox‐active hexaazatrinaphthylene (HATN) polymer with a surface area of 302 m2 g−1 and a very high bulk density of ca. 1.60 g cm−3. Uniquely, HATN polymer has a similar redox potential window to S, which facilitates the binding of Li2Sx and its transformation chemistry within the bulky polymer host, leading to fast Li2S/S kinetics. The compact polymer/S electrode presents a high sulfur loading of ca. 15 mgs cm−2 (200‐μm thickness) with a low cathode porosity of 41 %. It delivers a high areal capacity of ca. 14 mAh cm−2 and good cycling stability (200 cycles) at electrolyte–sulfur (E/S) ratio of 5 μL mgs−1. The assembled pouch cell delivers a cell‐level high energy density of 303 Wh kg−1 and 392 Wh L−1.