Although numerous papers have reported that graphene is a superior anticorrosion nanofiller, it has also been demonstrated that graphene cannot be used as a long-term anticorrosion barrier due to its essential high conductivity. Herein, an anticorrosive nanofiller (BNQDs@hBN) combining the nanomaterial boron nitride quantum dots (BNQDs) with insulating hexagonal boron nitride (hBN) is put forward. The homogeneous dispersion of BNQDs@hBN in an epoxy matrix was achieved with the assistance of BNQDs, and was based on strong π–π interactions between h-BN and BNQDs, as confirmed via UV-vis spectra. Embedding a small percentage of BNQDs@hBN in a waterborne epoxy (WEP) coating effectively improves the barrier properties of the coating by inhibiting the penetration of corrosive ions. Polarization tests revealed that the protection efficiency and corrosion rate of an epoxy coating with 0.5 wt% BNQDs@hBN were 99.99% and 6.482 × 10⁻⁵ mm year⁻¹, respectively. Electrochemical impedance spectroscopy (EIS) results demonstrated that the 0.5 wt% BNQDs@hBN coating system showed a higher impedance modulus (>10⁷) than that of a blank specimen after immersion for 60 days in 3.5 wt% NaCl_(aq).