Electromagnetic interference (EMI) shielding films with excellent mechanical properties are highly promising for applications in flexible devices, automotive electronics and aerospace. Inspired by the excellent mechanical properties of nacre derived from its micro/nanoscale structure, high-performance MXene/Cellulose nanocrystals (CNC) composite films were prepared by simple solution blending and followed vacuum-assisted filtration process. The presence of CNC significantly improves the mechanical properties with tensile strength increasing from 18 MPa to 57 MPa and toughness improving from 70 kJ/m ³ to 313 kJ/m ³. Meanwhile, the composite film still exhibits high electrical conductivity (up to 10 ⁴ S/m) and excellent EMI shielding efficiency (over 40 dB) with a small thickness of 8 μm.