Clinical applications of magnesium (Mg) alloys have been severely limited by their rapid corrosion in physiological environments. Superhydrophobic coatings can prevent water from contacting the Mg alloy surface, retarding alloy corrosion. In this study, a superhydrophobic Mg alloy was prepared by depositing fluorine-modified SiO2 nanoparticles (SiO2-F NPs) with polydopamine (PDA). The dip-coating strategy presented is simple, green, can be undertaken without any complex equipment, has reduced power consumption, and decreased threat to human health. The as-prepared superhydrophobic Mg alloy is resistant to corrosion in simulated body fluid (SBF). The superhydrophobicity was stable after the tape, water-impact and sand-impact tests over multiple cycles. In addition, cytotoxicity investigations demonstrated that the superhydrophobic Mg alloy exhibited excellent cytocompatibility. This work opens up a new avenue in the design of superhydrophobic Mg alloys for corrosion resistance.