Boron nitride nanosheets (BNNSs) have many outstanding properties for corrosion protection. Herein, multi-layer BNNSs are synthesized by a liquid-exfoliation method and serve as highly-effective nanofillers for polyvinyl butyral (PVB) coatings. Electrochemical characterizations reveal that the corrosion rate of copper protected by BNNSs/PVB composite coating is 5 orders of magnitude lower than that protected by pristine PVB coating. Raman spectra show no corrosion products formed on copper beneath PVB coating which is reinforced with more than 0.5 wt% BNNSs. We believe this study opens a new avenue for developing highly-impermeable polymeric composites for corrosion protection. (C) 2015 The Electrochemical Society.