In this work, crosslinkable polybenzoxazine (PBz), which exhibits high surface-covering ability, strong adhesion to metal substrates, and a dense crosslinked structure resistant to corrosion molecule permeation, has been demonstrated as an effective agent for single-component anticorrosion application. Plain crosslinked PBz-based anticorrosion coating shows a protection efficiency of 96.3%. Hierarchical surface structures and hydrophobicity have been introduced to the anticorrosion coatings through a biomimicking process using lotus leaves as templates, and so as to increase the protection efficiency to an extremely high level of 99.93%. Crosslinked PBz coatings with a hierarchical surface structure and surface hydrophobicity are highly effective for anticorrosion application. Moreover, biomimicking anticorrosion coatings have also been prepared with xanthosoma sagittifolium leaves to probe the template effect on the anticorrosion efficiency of the biomimicking coatings. Lotus leaves, rather than xanthosoma sagittifolium leaves, are the better choice for fabrication of the biomimicked anticorrosion coatings.