Dielectric materials with enhanced energy storage performances are urgently demanded owing to the development of advanced capacitor equipment. However, low energy density and weak self-healing capabilities of current dielectric materials still limit the practical applications. Here, a biaxially oriented (polypropylene/two-dimensional (2D) Al₂O₃ nanosheets/grafted polypropylene) nanocomposite was proposed. The biaxial orientation enabled the directional arrangement of nanosheets in the polymer matrix. The oriented 2D nanosheets played a dominate role in the restriction of charge transportation and the tradeoff of energy consumption during breakdown and self-healing. Therefore, on one hand, the discharge energy density reached a considerable value of 9.64 J/cm³. On the other hand, the self-healing area of the metalized films was a 36% smaller than that of biaxially oriented polypropylene (BOPP) at the comparable self-healing energy, which was related to the long-term reliability of capacitor. The further experiments and simulations indicated that the oriented γ-A₂O₃ nanosheets (AONs) arrangement suppressed electric field distortion and hindered the charge transportation, which greatly enhanced the breakdown strength and ultimately improved the energy storage performance. This strategy presented a potential solution for improving the energy storage performance of capacitor films, which is suitable for current industrial production.