Development of highly efficient adsorbent materials for the wastewater treatment is an excellent, cheap, environmental friendly and sustainable approach. Herein, a novel cotton flower-like hierarchically porous boron nitride (BN) structure was successfully synthesized by pyrolizing a boric acid/melamine mixture at 1100 °C in a controlled flow rate ratio of N2/H2. The obtained porous BN material with a large specific surface area (SSA) of 1140 m2 g−1 exhibited high selectivity, fast adsorption rate (∼96% for methylene blue (MB) after 20 min and ∼80% for rhodamine B (RhB) after 10 min) and high adsorption capacities (∼471.2 and 313.4 mg⋅g−1 for MB and RhB, respectively). The excellent selectivity of porous BN material towards dyes adsorption was confirmed from a mixed solution of dye and inorganic salts. In addition, porous BN material remain sustained without losing its adsorption activity even after 10 cycles and exhibited easy regeneration and good reusability which were achieved by a simple heating process. The obtained results indicated that the present porous BN material is a potential candidate for the removal of organic pollutants in water treatment applications.