The pristine montmorillonite (P-Mt) was modified with sodium dodecyl benzene sulfonate (SDBS) to form SDBS montmorillonite (SDBS-Mt) for the purpose of enhancing the removal performance of Cu(II) from aqueous solution. The materials were characterized by means of XRD, SEM-EDS, BET, and FTIR to analyze the surface morphology and structure. SDBS-Mt displayed a higher adsorption capacity than P-Mt. The adsorption kinetic model and the adsorption isotherm model are depicted by the pseudo-second-order kinetic equation and the Langmuir equation, respectively. The adsorption of Cu(II) on SDBS-Mt is a spontaneous and endothermic process. The order of influence of coexisting cations on the adsorption of Cu(II) is Ni(II) > Co(II) > Zn(II). In addition, the adsorbent has great regeneration performance after five cycles of regeneration. The main mechanisms of Cu(II) adsorption by SDBS-Mt may include electrostatic attraction, ion exchange, and complexation of sulfonate groups. In brief, SDBS-Mt may be a promising, simple, and low-cost adsorbent for the treatment of Cu(II) in aqueoussolutions.