We have seen a rapid surge in the growth and subsequent drive-in scaling down electronic interfaces with intelligent electronic devices. Any electronic gadget that transmits, distributes, or uses electrical energy produces electromagnetic interference (EMI), which has harmful effects on device performance, human health, and the surrounding environment. This increase in unrestricted EM pollution can also affect human well-being and the surrounding environment if proper shielding is not provided. Therefore, there is an increasing demand for EMI shielding materials due to the rapid increase in EM radiation sources. EMI shielding materials must have the capability to absorb and reflect EM radiation at very high frequencies and act as a shield against the penetration of radiation through them. The polymer matrices are generally electrically insulating; therefore, they cannot provide shielding against EM radiations. Thus, the use of electrically conducting fillers enables the path in polymer composites to shield the EM radiations. This chapter covers the up‐to‐date research activities targeting EMI shielding based on thermoplastic, and thermoset polymer nanocomposites (PNCs) reinforced with carbon-based nanostructures (CBNS). The first section of this chapter gives a brief overview of the fundamentals of EMI shielding, theoretical aspects of shielding, and different strategies for controlling EM radiations. Other synthesis methods are discussed in the next section, which deals with the preparation of PNCs. Comprehensive justification of potential materials for controlling EMI is also described with nanocomposites based on thermoplastic and thermoset polymer matrices incorporated within CBNS, magnetic, dielectric, and hybrid materials. The synergistic effects of the hybrid fillers may render tunable electrical conductivity and electrical percolation phenomenon in nanocomposites.