Abstract In this paper, an efficient adsorbent, iron-modified activated carbon fiber (Fe2O3/ACF), was rapidly fabricated by microwave-assisted heating treatment strategy, which is used to remove As(V) from simulated wastewater. The adsorbent was characterized by scanning electron microscopy (SEM), TEM, N2 sorption, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The characterization results showed that rod-like Fe2O3 particles in sizes of about 20 nm × 50 nm were homogeneously anchored on the surface of ACF. The goal of high As(V) removal efficiency was achieved with maximum adsorption capacity of 20.33 mg g−1. The effects of temperature on thermodynamics and kinetics of As(V) adsorption were systematically studied. It was found that the adsorption of As(V) on the surface of Fe2O3/ACF is an endothermic process with a standard enthalpy change (ΔH0) of 24.79 kJ mol−1. Batch experimental result showed that almost all of the As(V) with initial concentration of 3.0 mg L−1 can be removed in the presence of Fe2O3/ACF, where the residual As(V) in filtrate was less than 0.01 mg L−1, below the tolerance level of drinking water suggested by World Health Organization (WHO). The presence of salt such as NaCl, Na2SO4, and MgSO4 showed little effects on the adsorption of As(V), indicating the promising application of Fe2O3/ACF in industrial wastewater.