With the rapid development and popularization of smart, portable, and wearable flexible electronic devices, urgent demands have been raised for flexible electromagnetic interference (EMI) shielding films to solve related electromagnetic pollution problems. With polyvinyl alcohol (PVA) as polymer matrix, the sandwich‐structured EMI shielding nanocomposite films are prepared via electrospinning‐laying‐hot pressing technology, where Fe₃O₄/PVA composite electrospun nanofibers in the top and bottom layers and Ti₃C₂T_x/PVA composite electrospun nanofibers in the middle layer. Owing to the electrospinning process and the successful construction of the sandwich structure, when the amounts of Ti₃C₂T_x and Fe₃O₄ are respectively only 13.3 and 26.7 wt%, the EMI shielding effectiveness (EMI SE) of the sandwich‐structured EMI shielding nanocomposite films reach 40 dB with the thickness of 75 µm, higher than that of (Fe₃O₄/Ti₃C₂T_x)/PVA EMI shielding nanocomposite films (21 dB) prepared based on blending‐electrospinning‐hot pressing process under the same amounts of fillers. Furthermore, the prepared sandwich‐structured EMI shielding nanocomposite films possess excellent thermal conductivities and mechanical properties. This novel kind of flexible sandwich‐structured EMI shielding nanocomposite films with excellent EMI shielding performances, thermal conductivities, and mechanical properties presents broad application prospects in the fields of EMI shielding and protection for high‐power, portable, and wearable flexible electronic devices.