<p>Olivine is a natural material with abundant reserves and is considered to have the potential to treat heavy metal ions in water. In this study, a facile precipitation-calcination method was employed to deposit micrometer-sized magnesium oxide (MgO) rods onto the surface of olivine powder (PO). This process yielded a cost-effective MgO-modified olivine composite (MgO@PO400), which was subsequently evaluated for its ability to adsorb Cu²⁺ from aqueous solutions. The BET-specific surface area of MgO@PO400 was three times higher than that of PO, and the MgO micro-rods were distributed on the material's surface (BET:Brunauer-Emmet-Teller). Adsorption experiments showed that the data fitted well with the pseudo-second-order kinetic model and the Langmuir isotherm model, which indicated that Cu²⁺ was removed by monolayer chemisorption. In addition, the process was verified to be spontaneous and thermodynamically favorable. The maximum adsorption capacity of MgO@PO400 for Cu²⁺ was 225.82 mg/g, which was able to exhibit high removal efficiency (84.95–98.05%) for Cu²⁺ in the pH range of 3 to 5.5, and good immunity to the presence of different coexisting ions in the water, demonstrating that potential for treating complex Cu2⁺-containing wastewater. Various characterization methods verified the adsorption mechanism of MgO@PO400 on Cu²⁺, and the results showed that the removal of Cu²⁺ mainly involved ion exchange, surface precipitation and electrostatic attraction. Therefore, MgO@PO400 can be considered a potential adsorbent for removing Cu²⁺ from aqueous solutions.</p> Graphical Abstract <p></p>