This study has demonstrated that the Fenton fluidized bed (FFB) technology could successfully immobilize As ions on the iron-crystallized (IC) carriers, with simultaneous crystallization of ferric and mineralization of organic pollutants. It was found that rapid fluidized immobilization of aqueous As(V) on the IC carriers was through surface favorable bidentate complexion, while the adsorptive removal of As(III) was rather slow. Adding Fe3+ caused competitive complexion and inhibited the As(V) immobilization. However, effective oxidative crystallization of Fe(II) and As(III) in FFB would take place. With the simultaneous generation of As(V) and Fe(III) by rapid •OH oxidation, two different crystalline precursors would be formed on the IC carriers, leading to efficient co-crystallization of As(V)/Fe(III). Recursive Fe(III) crystallization in the FFB continuously provided essential surface hydroxyl groups for capturing As(V), inducing layer-by-layer co-crystallized immobilization As(V)/Fe(III). The long-term continuous-flow treatment of a practical As(III)-containing industrial organic wastewater exhibited effective/stable co-crystallizations of As(V)/Fe(III), as well as COD removal. The FFB technology is expected to be a good option in treating complex industrial wastewater containing heavy metal and recalcitrant organic pollutants.