With the rapid development of industrial production, toxic hexavalent chromium (Cr(VI)) has become one of primary pollutants in wastewater. Carbon materials are widely used to remove the Cr(VI) from wastewater through adsorption, which is recognized as a facile, cost-efficient and high-selectivity approach. Herein, a novel hierarchically porous activated carbon (denoted as ACDW) was fabricated via a scalable strategy that combines a chemical delignification with the subsequent carbonization and KOH activation, in which the waste poplar sawdustsawdust was used as carbon precursor. Systematic analyses were carried out by using Scanning Electron Microscope, Energy Dispersive Spectroscopy, X-ray Diffraction Spectroscopy, N₂ Adsorption and Desorption, Fourier Transform Infrared Spectroscopy and X-ray Photoelectron Spectroscopy to reveal the morphology, structure and physicochemical properties of the resultant carbon materials. By virtue of the unique multilayer and honeycomb porous structure induced by delignification and activation process, the resultant ACDW exhibits a high specific surface area of 970.52 m² g^–1 with abundant meso- and micropores. As a benign adsorbent for the uptake of Cr(VI) in wastewater, ACDW delivered a remarkable adsorption capacity of 294.86 mg g^–1 in maximum, which is significantly superior than that of unmodified counterparts and others reported carbon materials. Besides, the adsorption behavior fitted better with the Langmuir isotherm, pseudo-second-order kinetic model and adsorption diffusion model in a batch experiment. Based on the results, we put forward the conceivable adsorption mechanism that the synergistic contributions of electrostatic attraction, chemical complexation, ion exchange and reduction action facilitate the capture of Cr(VI) by ACDW.