Environmental problems caused by excessive carbon dioxide emissions demand more than attention but realistic plans and specific actions as well. The development of materials with an efficient CO2 adsorption performance is significant. In this paper, boric acid and ethylenediamine are used as boron and nitrogen sources, respectively, without using a hard/soft template, and a simple hydrothermal carbonization method is used to synthesize hierarchical porous carbon materials double-doped with boron and nitrogen. The cooperative effect between the doped elements and the well-developed porous structure leads to the excellent CO2 capture ability of the prepared adsorbent. Notably, the material also exhibits impressive cyclic stability, revealing the feasibility of its use in practical applications.