The addition of magnesium to Aluminum alloys has become increasingly popular due to their lightweight, high strength, and corrosion resistance properties. Our research on high-content Mg doped 90, Al-10 wt% Mg alloy has shown that coating it with electroless Ni-P and codepositing nano-Al2O3 (0, 2.5, 5 and 7.5 wt%) can significantly improve its mechanical properties, resistance to wear & tear, and even corrosion resistance. The electroless Ni-P-5 wt% Al2O3 composite displayed a wear rate of 0.65×10−3 g/m at 12 N, a microhardness value of 598 HV, and remarkable thermal shock resistance. A strong and uniform bond was formed between the coating and substrate, and no delamination or cracking was observed. Polarisation curves in 3.5 wt% NaCl solution showed that the corrosion potential of the 90, Al-10 wt% Mg alloy was higher than that of Ni-P and Ni-P-nano Al2O3 composites, indicating that the incorporation of nano-Al2O3 into the Ni-P electroless bath provides superior corrosion protection. This cost-effective and simple approach makes the Ni-P-5 wt% Al2O3 nanocomposite coating an ideal choice for shielding Al-Mg alloys from corrosion. HIGHLIGHTS We examine the magnesium content in Al-Mg alloy Electroless Ni-P-5 wt% Al2O3 coating could improve the anti-corrosion properties of Al-Mg alloy The thermal shock test showed that the alloy had good thermal stability Microhardness and wear resistance increase with the addition of nano Al2O3 particles The electroless Ni-P-5 wt% Al2O3 composite shows a wear rate of 0.65×10−3 g/m at 12 N GRAPHICAL ABSTRACT