AbstractThe BiS₂‐based layered superconductors with structures similar to those of cuprates and iron‐based superconductors have stimulated much research interest. Here, a new quaternary compound is reported, Bi₅O₄S₃Cl, which crystalizes in a tetragonal structure with P4/mmm (No. 123) space group having alternately stacking unique BiS₃ layers and Bi₂O₂ layers along the c‐axis with a Cl atom located at the center of the unit cell. A superconducting transition above 3 K is observed for both electrical transport and magnetic measurements. Hall resistivity measurements show its multiband character with a conduction dominated by electron‐like charge carriers. The first‐principles calculations exhibit that the semiconducting parent phase Bi₅O₄S₃Cl becomes metallic when sulfur vacancies are introduced, which hints the origin of superconductivity in Bi₅O₄S₃Cl. The findings will inspire the exploration of new BiS‐based superconductors.