This study investigates the enhancement of electromagnetic wave absorption in SiC@MoO₃ nanocomposites through defect engineering, specifically by creating oxygen vacancies within the MoO₃ layer. The research involves the electro-deposition of MoO₃ onto SiC nanowires followed by high-temperature calcination. The introduction of oxygen vacancies is achieved through in-situ etching with KBH₄, resulting in samples with varying oxygen vacancy concentrations (SiC@MO-t2, SiC@MO-t4, SiC@MO-t6, and SiC@MO-t8). These samples exhibit improved electromagnetic wave absorption properties, with SiC@MO-t4 showing a minimum reflection loss of -50.49 dB at a thickness of 1.27 mm and SiC@MO-t6 achieving an effective absorption bandwidth of 8.72 GHz over the Ku band at a thickness of 2.81 mm. The enhanced performance is attributed to the increased conductivity and induced dipole polarization losses due to the oxygen vacancies, which modulate the electronic structure and improve impedance matching. Density functional theory (DFT) calculations support these findings by showing how oxygen vacancies reduce the band gap and induce charge transfer, enhancing the dielectric loss and electromagnetic wave attenuation. This study provides a systematic approach to improving electromagnetic wave absorption through defect engineering in TMOs.This study investigates the enhancement of electromagnetic wave absorption in SiC@MoO₃ nanocomposites through defect engineering, specifically by creating oxygen vacancies within the MoO₃ layer. The research involves the electro-deposition of MoO₃ onto SiC nanowires followed by high-temperature calcination. The introduction of oxygen vacancies is achieved through in-situ etching with KBH₄, resulting in samples with varying oxygen vacancy concentrations (SiC@MO-t2, SiC@MO-t4, SiC@MO-t6, and SiC@MO-t8). These samples exhibit improved electromagnetic wave absorption properties, with SiC@MO-t4 showing a minimum reflection loss of -50.49 dB at a thickness of 1.27 mm and SiC@MO-t6 achieving an effective absorption bandwidth of 8.72 GHz over the Ku band at a thickness of 2.81 mm. The enhanced performance is attributed to the increased conductivity and induced dipole polarization losses due to the oxygen vacancies, which modulate the electronic structure and improve impedance matching. Density functional theory (DFT) calculations support these findings by showing how oxygen vacancies reduce the band gap and induce charge transfer, enhancing the dielectric loss and electromagnetic wave attenuation. This study provides a systematic approach to improving electromagnetic wave absorption through defect engineering in TMOs.