Superparamagnetic iron oxide nanoparticles have been found suitable as adsorbent materials for the removal of As(III) from aqueous solution. In this investigation, the usefulness of magnetically doped epoxide functional cross-linked poly(lauryl methacrylate) (PLMA) composite polymer particles as an adsorbent bed for the removal of As(III) ions has been evaluated. The epoxide functional composite polymer particles are prepared by seeded polymerization of glycidyl methacrylate (GMA) in the presence of cross-linked poly-(LMA-divinylbenzene), P(LMA-DVB), seed particles. The surface of prepared. composite polymer particles is finally doped with Fe3O4 nanoparticles. The epoxide functional magnetic composite polymer particles have been named as P(LMA-DVB)/PGMA/Fe3O4. A pH and contact time dependent adsorption behavior of As(III) is observed on P(LMA-DVB)/PGMA/Fe3O4 composite polymer particles. The equilibrium (q(e)) reached after 180 min and a highest removal efficiency of 57.98% is attained at pH 5.0. The adsorption isotherm strictly followed Langmuir model with maximum theoretical adsorption capacity (q(m)) reaching 66.23 mg/g of particles at 323 K. Batch kinetic sorption experiments showed that a pseudo-second-order rate kinetic model is more applicable. The study of thermodynamic equilibrium parameters suggested that adsorption of As(III) is endothermic and spontaneous. The adsorbent could be regenerated partially by treatment with 0.01 M NaOH, retaining about 40% of the adsorption capacity after first time adsorption and then only slightly decreased.