<p>In this study, Fe₃O₄ magnetic particles (MPs) were produced from nickel slag using molten oxidation and magnetic separation methods. After that, Fe₃O₄ MPs were coated with a blend of poly (butylene adipate-co-terephthalate)/beta-cyclodextrin/polyvinyl alcohol (PBAT/B-CD/PVA), and Mg²⁺ was doped during this process. Mg²⁺-Fe₃O₄@PBAT/B-CD/PVA MPs were then modified using γ-glycidoxypropyltrimethoxysilane (KH560) to produce Mg²⁺-Fe₃O₄@PBAT/B-CD/PVA-g-KH560 MPs. The immobilized PGA (Mg²⁺-Fe₃O₄@PBAT/B-CD/PVA-g-KH560-PGA MPs) was obtained through covalently bonding PGA under mild circumstances by a click reaction between the amino group of PGA and the epoxy group of KH560. Furthermore, a vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy-energy spectroscopy of dispersive x-rays (SEM–EDS), X-ray photoelectron spectrophotometry (XPS), and inductively coupled plasma mass spectrometry (ICP-MS) were used to characterize the magnetic composite structures. The results showed that the immobilized PGA had values of 31,574 U/g, 94.2%, and 113&#xa0;mg/g for enzyme activity recovery (<i>EAR</i>), enzyme loading capacity (<i>ELC</i>), and enzyme activity (<i>EA</i>), respectively. Its enzyme activity was maintained at 74% after 12 cycles of usage. The Fe₃O₄@PBAT/B-CD/PVA MPs were prepared similarly to the preparation of Mg²⁺-Fe₃O₄@PBAT/b-CD/PVA MPs except that Mg²⁺ was not doped to it to adopt as control, and after 6 cycles of usage, the immobilized PGA (Fe₃O₄@PBAT/B-CD/PVA-g-KH560-PGA MPs) retained 50% of its original enzyme activity, with <i>EA</i>, <i>EAR</i>, and <i>ELC</i> values of 28,513 U/g, 85.2%, and 107&#xa0;mg/g, respectively, which were lower than Mg²⁺-Fe₃O₄@PBAT/B-CD/PVA-g-KH560 MPs; this indicate that doped Mg²⁺ had positive impact on immobilized PGA.</p> Graphical Abstract <p>Preparation scheme of immobilized PGA (Mg⁺²-Fe₃O₄@PBAT/B-CD/PVA-g-KH560-PGA MPs)</p> <p></p>