It is of significance to prepare biodegradable electromagnetic interference (EMI) shielding materials with high EMI shielding effectiveness (SE) in order to solve electromagnetic and environmental pollution problems. In this paper, environmentally friendly EMI shielding silver nanowires (AgNWs)/poly(L-lactic acid) (PLLA)/poly(D-lactic acid) (PDLA)/ferroferric oxide (Fe₃O₄) composites with step-wise asymmetric structures were prepared by a facile one-step non-solvent-induced phase separation method. The conductive AgNW network was constructed at a low mass fraction of 5 wt.% on the surface of stereo-complexed crystalline poly(lactic acid) (SC-PLA) film (1.08 × 10⁴ S/m). Moreover, magnetic Fe₃O₄ is mainly distributed in the skeleton of porous SC-PLA film. Due to the synergistic effect of AgNWs and Fe₃O₄, the EMI SE of SC-PLA films reaches up to 50.3 dB. Interestingly, SC-PLA film modified with triethoxy-1H,1H,2H,2H-tridecafluoro-n-octylsilane (TTO) demonstrates an outstanding water contact angle of about 150.2° compared with the pure PLLA film (134.7°), stemming from the synergistic effect of denser SC-PLA nano-protrusions and low-surface-energy TTO. Thus, we successfully fabricated the high EMI shielding SC-PLA film with wonderful superhydrophobicity, which extends the application performance and service life of portable electronics in moist environments.