Linear dielectric polymers are potential candidates for electrostatic capacitors due to their high breakdown strength, high efficiency, and low dielectric loss. In this work, a novel poly (vinylidene fluoride) (PVDF) tailored linear PMMA-co-GMA (MG) copolymer-based all-organic dielectric film with high breakdown strength and discharge energy density was prepared by the solution blending method. Compared with the PMMA homopolymer, the MG copolymer behaved with a higher energy density (5.6 J/cm3) since the GMA component bestowed higher polarity and yielded deep traps for the copolymer. On the other hand, the introduction of PVDF into MG further improved the dielectric constant and overcame the brittleness of MG films. When the concentration of PVDF was 30 wt %, the MG/PVDF film exhibited a high discharged energy density of 10.8 J/cm3 at 600 MV/m with a 78.7% discharge efficiency, which was 2.5 times that of pure PVDF (4.3 J/cm3 at 320 MV/m) and 1.9 times that of pure MG (5.6 J/cm3 at 460 MV/m). The improvement in energy storage performance might be ascribed to the excellent thermodynamic miscibility and hydrogen bond interaction between the linear MG copolymer and the ferroelectric PVDF. This research provides a new and feasible strategy for designing all-organic dielectric films with high energy density for energy storage applications.