<p>Pure polymers are limited in dielectric field applications due to their low dielectric constant, poor thermal conductivity, and instability, as well as their inefficient energy storage density for energy storage, high-voltage insulation, and EMI shielding. However, dielectric polymers appear to have low loss, fast charge and discharge speed, chemical stability, and good flexibility; therefore, they play a key role in power electronics and pulse power systems as a promising energy storage device. One effective way to address the shortcomings of pure polymers in electrical applications is by incorporating inorganic fillers into their matrix. Inorganic fillers can enhance properties such as dielectric constant, breakdown strength, and thermal conductivity, depending on their type and characteristics. Inorganic fillers can be categorized into four general groups. Incorporating each of these groups of fillers into polymer matrices can enhance certain key properties while simultaneously diminishing some desirable characteristics of the polymer. It is essential to have a comprehensive understanding of the fundamental principles and core concepts of dielectrics to effectively improve their attributes for the design and manufacture of devices. Considering this goal, we briefly reviewed the fundamentals of dielectric materials, the influence of the inorganic fillers on polymer properties, and recent advances in this field.</p> Graphical abstract <p></p>