<p>Magnesium (Mg) alloys exhibit high corrosion susceptibility, while conventional superhydrophobic coatings depend on harmful fluorinated materials and petrochemical-derived binders, which together limit sustainable application. To address these issues, a bio-based bilayer superhydrophobic coating (HASM) was fabricated on the surface of AZ31B magnesium alloy via spraying. The coating consists of a protective bottom layer formed by physically blending the soy-mal-tan (SMT) bio-based adhesive with the corrosion inhibitor 2-mercaptobenzimidazole (2-MBI), and a fluorine-free superhydrophobic top layer composed of attapulgite (ATP) modified with hexadecyltrimethoxysilane (HDTMS). The coating retained a water-repellent surface after 55 abrasion cycles, 65 tape-peeling cycles, and 60&#xa0;days of outdoor exposure. Enabled by the synergistic effects of the superhydrophobic barrier and the inhibitor-containing underlayer, the HASM coating exhibited anticorrosion performance, reaching a low-frequency impedance modulus (|Z|_{<i>f</i>&#xa0;=&#xa0;0.01}) of 9.07 × 10⁷&#xa0;Ω&#xa0;cm² and maintaining 1.16 × 10⁴&#xa0;Ω&#xa0;cm² after 21&#xa0;days in 3.5 wt% solution of NaCl, which is approximately two orders of magnitude higher than that of bare AZ31B Mg alloy. This study demonstrates highly effective protection by the HASM coating and offers a sustainable route to designing high-performance, fluorine-free anticorrosive coatings for AZ31B Mg alloys.</p> Graphical Abstract <p></p>