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Lightweight carbonized wood has a hierarchically 3D porous framework and orthotropic channels along the growth direction, which demonstrate great potential for multifunctional electronic materials. Herein, carbonized wood with outstanding electromagnetic interference (EMI) shielding effectiveness (SE), high thermal conductivity, and excellent Joule heating property is fabricated. It also exhibits a highly anisotropic EMI shielding performance in the cross‐ and tangential‐sections. In the tangential‐section, the shielding performance of carbonized wood is tuned by monitoring the angle between the wood grain and the electric field vibration direction of the electromagnetic waves, and the SE value ranges from 29 to 77 dB when the angle changes from 90° to 0°. Benefiting from the high SE obtained from structural optimization and the low density, carbonized balsa wood displays a high SSE (the ratio of SE to density) and SSE/t (the ratio of SSE to thickness) of 1069 dB cm3 g−1 and 3263 dB cm2 g−1, respectively. The thermal conductivity of carbonized wood is also angle‐dependent, which ranges from 0.865 to 1.897 W m−1 K−1. With the improvement in thermal conductivity, carbonized wood can be used as a heat sink material. Meanwhile, excellent Joule heating properties are achieved due to the effective conductive pathway in carbonized wood.

To comply with the increasingly complex and changeful application environment, realizing effective shielding effectiveness (SE) adjustment is the trend of next-generation electromagnetic interference (EMI) shielding materials. Herein, we utilize the natural wood as substrate, and MXene sheets are coated to the wood surface to develop anisotropic MXene@wood (M@W) composites with outstanding EMI shielding performance. The M@W displays apparent different properties between cross section and tangential section, in terms of pore structure, dielectric properties, polarization relaxation, impedance matching condition, and EMI SE. In the tangential section, the angle between wood grain and the electric field direction of incident electromagnetic wave governs the shielding performance. The EMI SE ranges from 57.6 dB to 27.4 dB when the angle changes from 0° (parallel to grain of wood) to 90° (perpendicular to grain of wood). This finding provides invaluable guidance for the design of anisotropic materials with convenient EMI shielding performance regulation.