Potassium-sulfur (K-S) battery represents one of the most promising electrochemical energy storage devices because of the low cost and abundance of potassium and sulfur resources, but the inferior cycle stability and high operating temperature seriously impede its applications. Herein, a high energy and stable room temperature K-S battery was developed with a confined ad covalent sulfur cathode, which could deliver an energy density as high as ∼445 Wh Kg−1, a Coulombic efficiency close to 100%, and a superior cycle stability with a capacity retention of 86.3% over 300 cycles at a voltage cut-off of 0.8–3.0 V. This work displayed a basic study on the rechargeable potassium-sulfur batteries and may pave the way for designing sulfur based electrode materials for potassium based ion batteries.