Herein, we proposed phosphorene-oxide-based nanoadsorbents for the simultaneous removal of highly toxic inorganic As(III) and As(V) species from water. Employing density functional theory (DFT) calculations, it is studied the adsorbent-adsorbate stability, interaction mechanisms, arsenic mobility, and sorbent regeneration. The proposed nanoadsorbents show unique advantages: i) adsorption mechanism via inner-sphere surface complexation; ii) strong adsorption efficiency with a medium oxidation degree (oxygen content); iii) high recovery ability by simple treatment methods with alkaline eluents. Then, phosphorene-oxides turn into remarkable candidates for further control and remediation technologies of arsenic contamination from water.