In this paper, a corrosion-resistant film (the cerium/bis-silane composite film) was fabricated on sintered NdFeB substrate by a simple and effective one-step film preparation method. The method uses an electrochemically assisted deposition technology to create superhydrophobic micro/nanostructures, during which the electrochemical oxidation of rare earth ions produces oxides and hydroxides to be deposited in the film layer. The experiment results show that the cerium/bis-silane composite film exhibited superhydrophobicity (hydrophobicity angle of 152°) and high corrosion resistance. The Icorr values for the cerium/bis-silane composite film is 1.81 × 10−6 A/cm2 with an inhibition efficiency of 74.6%. By characterising the morphology of its surface and cross-section, it can be observed that the cerium/bis-silane composite film is thicker and more uniform than the bis-silane (Ethyl orthosilicate (TEOS) + Dodecyltrimethoxysilane (DTMS)) film. Additionally, due to its superhydrophobic surface, 3D network structure, and alkaline passive layer, the cerium/bis-silane composite film was highly effective in preventing the infiltration and diffusion of corrosive ions. Furthermore, the cerium/bis-silane composite film has very little influence on the magnetic properties of the sintered NdFeB, being a hopeful candidate for the new environment-friendly protective coatings to be used in the NdFeB and related industries.