Among various environmental problems, water pollution has drawn more and more attention. To develop an adsorbent with enhanced selectivity and high capacity for As (V) oxyanion, a novel lignin-based adsorbent was prepared by doping with N and modifying with Mg2+, using thiethylenetetramine (TETA) and MgCl2 as the source of N and Mg2+, respectively. N-doped lignin (NL) shows a high selectivity for As (V), which is further enhanced by modifying with Mg2+ (MNL). MNL shows an excellent reusability. The adsorption isotherms and kinetics of MNL for As (V) follow Langmuir isotherms model and pseudo-second-order kinetics model, respectively. The adsorption of MNL for As (V) achieved a maximum adsorption capacity of 687.46mgg−1 and the equilibrium was established within 30min. This study offers a novel idea on the recycle of the waste of paper industry and provides a new technology for As (V) adsorption from wastewater.