Inspired by the oriented structure and strong interface of nacre, we prepared polydopamine (PDA)-coated boron nitride nanoplatelets (BNNS@PDA)/polyvinyl alcohol (PVA) composite films with a unique nacre-like structure via a facile vacuum-assisted self-assembly process. Few-layer BNNSs were obtained by exfoliating BN platelets via low-energy ball milling and sonication. Subsequently, PDA coating was deposited onto the surface of the BNNSs to ameliorate the interaction between the BNNS@PDA and PVA matrix. The resultant BNNS@PDA/PVA composite film displayed a superior in-plane thermal conductivity of 24.6 W m⁻¹ K⁻¹ at a filler content of 70 wt%. The strong alignment of the BNNSs provided the structural basis for phonon conduction, and more importantly, the high affinity of the PDA coating improved the interfacial connection between adjacent fillers. Based on the Foygel nonlinear model, the interfacial thermal resistance of the BNNS@PDA/PVA films was 33% lower than that of their BNNS/PVA counterparts. Moreover, the BNNS@PDA/PVA films exhibited high mechanical flexibility, fatigue reliability, and solvent stability. The retention ratio of the in-plane TC was 98% after repeated bending-release cycles and 87% after 10 h of solvent soaking. Our BNNS@PDA/PVA films showed great potential for applications in the burgeoning field of flexible and highly powered electronics.