Novel surface insulated 0.5(BaCa)TiO-0.5Ba(ZrTi)O (BCZT) nanofibers adhered with boron nitride nanosheets (BNNSs), named as BCZT@BN, is used as fillers in polyvinylidene fluoride (PVDF)-based nanocomposites. Double layered film which comprises high breakdown strength (E) layer of PVDF/0.8 wt% BNNSs (PBN) and high dielectric constant (ε) layer of PVDF/0.4 wt% BNNSs/zwt% BCZT@BN (PBNBCZT@BN) is employed. The E is largely increased from 380 MV m of pristine PVDF film to 730 MV m of PVDF nanocomposite fed with 0.8 wt% BNNSs, and a high discharge energy density (U) of 17.9 J cm is achieved at the same time. Furthermore, after introducing 1.6 wt% BCZT@BN in PBN-PBNBCZT@BN nanocomposites, the ε reaches up to 10.7, which is substantially improved by 119% over that of PBN nanocomposite (9.1). Thus, the incorporation of BCZT@BN NFs endows the PBN-PBNBCZT@BN nanocomposite with an impressive energy storage density (U) of 24.3 J cm, which is 3.57 times of pristine PVDF. Finite element simulation analysis reveals that BNNSs adhered on the surface of BCZT NFs exhibit a prominent effect in local electric field elimination and leakage current density dispersion. The strategy provides an innovative approach to enhance the energy storage performance of polymer-based nanocomposites.