With a strong ability in tailoring molecular structure, nanoscale morphology, and nanodomains, the ferromagnetic metal-organic framework (MOF, M = transition metal) has been considered an advantageous candidate material for dielectric nanocomposites. Herein, a pristine content-controlled Ag nanoparticle driving Ni metal-organic framework (Ag-NiMOF) ultra-thin 2D ferroelectric nanoplatelets have been synthesized by a two-step method, and applied to the PVDF-based energy storage materials. Comprehensive tests and multi-physics simulations have been conducted on the electrical properties of materials. The electric displacement-electric field (D-E) hysteresis loops of the composites show that the discharge density of 6.987 J/cm3 ~ 2300 kV/cm has been achieved with a 10 wt% filler addition, namely 10Ag-NiMOF/PVDF, which indicates a 5.36 times increase in the discharge density. Finite element simulation further verifies the improvement of the displacement and electrical breakdown strength of the composites. This high performance indicates that both of the centrosymmetric lattice nanodomains of NiMOF and the electrons introduced by Ag nanoparticle would help induce greater polarization in the nanocomposite. Furthermore, the Coulomb blockade effect exerted by the Ag nanoparticle with an appropriate particle size and a fractional concentration can significantly improve the electrical breakdown strength. This 2D hybrid particle provides a novel idea for modifying dielectric composites for high storage device applications. Display omitted •Ag Content-controlled ultra-thin 2D Ag-NiMOF ferroelectric nanoplatelets have been synthesized by a two-step method.•The discharge density of 6.987 J/cm3 ~ 2300 kV/cm has been achieved with a 10 wt% hybrid nanopalatets addition.•The centrosymmetric lattice nanodomains of NiMOF and the electrons introduced by Ag dots would help induce greater polarization in nanocomposite.•The Coulomb blockade effect exerted by the Ag dots with an appropriate size can significantly improve the electrical breakdown strength.