Carbon fiber (CF)-filled fiberboard specimens for electromagnetic (EM) shielding applications were produced in this study by mixing CF with wood fiber (WF). The aim of this work was to study the panel properties with different loadings (1%, 2%, 3%, 5%, and 10%) of CF. The mechanical, physical, and electromagnetic interference (EMI) shielding properties of the produced medium density fiberboard (MDF) were analyzed. The shielding effectiveness (SE) of the CF1 sample was 23.5 dB to 35.0 dB in the frequency range of 8.2 GHz to 12.4 GHz. The maximum SE of 64 GHz to 76 dB was obtained for the CF10 sample. The investigation of the mechanical properties of MDF panel indicated that the modulus of rupture (MOR), modulus of elasticity (MOE), and internal bonding (IB) of the composite panels were less than those of the control panel. The MOR, MOE, IB, thickness swelling (TS), and water absorption (WA) of the panel with 1% CF (CF1) were 24.7 MPa, 2,510 MPa, 0.69 MPa, 14.5%, and 52.3% respectively. Generally, the MDF panels with 1% CF exhibited a greater ability for EM shielding applications because of their acceptable properties according to the EN 622-5 (2019) standard and appropriate EM shielding of at least 20 dB.