As wearable electronics and wireless communications grow in popularity, high-performance electromagnetic interference (EMI) shielding materials are being explored for reducing serious radiation pollution. In this work, the high aspect ratio and high crystallinity of pineapple leaf nanofibers (PALNF), extracted and separated from the agricultural waste of pineapple leaves, are being considered potential dispersants and binders for assisting in the fabrication of ultrathin, highly flexible and mechanically robust Ti₃C₂T_x MXene/PALNF EMI shielding films. The “bricks-and-mortars” composite film containing only 50 wt % PALNF exhibits a superior tensile strength (up to 159.6 MPa), fracture strain (up to 6.7%), and toughness (up to 5.8 MJ/m³), which is several times or dozens of times higher than other reported freestanding MXene film. In particular, the composite film with a ratio of 1: 1 displays outstanding specific EMI shielding properties of 6541.1 dB cm² g⁻¹ in the X-band at a thickness of only 28 μm. Thus, from the perspective of “waste to wealth” and nacre bionics, recycling waste pineapple leaves through reprocessing into high-value EMI shielding films is a feasible way to reduce environmental problems caused by these wastes and electromagnetic radiation.