In this research, sawdust was modified with chemical reagents to produce an adsorbent from byproduct, namely, Al‐based nanoparticle‐impregnated sawdust (ANIS) to remove arsenate [As(V)] from aqueous solutions. Several methods, including scanning electron microscopy with an energy‐dispersive spectrometry, Brunauer–Emmett–Teller surface area analysis, and thermogravimetric analysis, were performed to characterize this material. Results showed that Al‐based nanoparticles were successfully impregnated in the sawdust and thus significantly changed their surface characteristics. Batch adsorption studies were conducted to determine the properties and mechanisms of As(V) adsorption onto ANIS. The maximum adsorption capacity of As(V) was 17.76 mg/g, which was higher than that of most adsorbents from byproducts. However, the adsorption of As(V) was adversely affected by alkaline conditions. Some interfering anions, especially phosphate, inhibited the ANIS‐induced As(V) removal. Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy suggested that the oxygen‐containing functional groups of Al oxides were the main contributors to As(V) adsorption, and the main adsorption mechanism was surface complexation. Approximately 2664 bed volumes of simulated groundwater containing 150 µg/L As(V) were treated before a breakthrough was observed in the small‐scale column experiments. Thus, ANIS could be an efficient material for As(V) removal. This study indicated that ANIS can be used as a reliable option for As decontamination. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1314–1322, 2017