Lightweight and flexible multifunctional materials with excellent electromagnetic interference (EMI) shielding and Joule heating performances are highly demanded for smart and wearable electronics. In this work, polyacrylonitrile (PAN) nanofiber films are prepared by electrospinning and then coated with polypyrrole (PPy) via vapor deposition, yielding a continuous three-dimensional (3D) conductive network of PAN@PPy. Ti3C2Tx MXene nanosheets with high electrical conductivity are sprayed on the PAN@PPy film to enhance its EMI shielding performance. The as-prepared PAN@PPy/MXene films (55 μm thick) exhibit a high EMI shielding effectiveness (SE) of 32 dB, achieving an extraordinarily high normalized surface-specific SE (SSE/t) of up to 17 534.5 dB cm2 g-1 from 8.2 to 12.4 GHz; simultaneously, the temperatures of PAN@PPy/MXene films can be driven up to 170.5 °C at an input voltage of 4 V, and exhibit fast-response, stable, and long-term Joule heating performance. The high SSE/t and efficient Joule heating ability of the films bode potential applications in smart and wearable devices.