This study presents a novel strategy for enhancing electromagnetic wave absorption using a SiC@MoO3 nanocomposite with oxygen vacancies. The nanocomposite was synthesized via electro-deposition and calcination, followed by in-situ etching with KBH4 to introduce oxygen vacancies. The presence of oxygen vacancies increases conductive loss and defect-induced dipole polarization, which significantly enhances electromagnetic wave absorption. The SiC@MO-t4 sample exhibited a minimum reflection loss of -50.49 dB at 1.27 mm thickness, while the SiC@MO-t6 sample showed an effective absorption bandwidth of 8.72 GHz at 2.81 mm thickness, covering the entire Ku band. These results demonstrate the importance of defect engineering in tuning electromagnetic properties for improved absorption performance. The study also reveals that oxygen vacancies contribute to enhanced electromagnetic wave absorption through induced dipole polarization and improved impedance matching. The findings provide valuable insights for the development of efficient, scalable electromagnetic wave absorption materials. The research highlights the role of oxygen vacancies in enhancing the dielectric loss and conductivity loss of the nanocomposite, leading to improved electromagnetic wave absorption performance. The study provides a systematic framework for using vacancy engineering to enhance the electromagnetic wave absorption properties of transition metal oxides.This study presents a novel strategy for enhancing electromagnetic wave absorption using a SiC@MoO3 nanocomposite with oxygen vacancies. The nanocomposite was synthesized via electro-deposition and calcination, followed by in-situ etching with KBH4 to introduce oxygen vacancies. The presence of oxygen vacancies increases conductive loss and defect-induced dipole polarization, which significantly enhances electromagnetic wave absorption. The SiC@MO-t4 sample exhibited a minimum reflection loss of -50.49 dB at 1.27 mm thickness, while the SiC@MO-t6 sample showed an effective absorption bandwidth of 8.72 GHz at 2.81 mm thickness, covering the entire Ku band. These results demonstrate the importance of defect engineering in tuning electromagnetic properties for improved absorption performance. The study also reveals that oxygen vacancies contribute to enhanced electromagnetic wave absorption through induced dipole polarization and improved impedance matching. The findings provide valuable insights for the development of efficient, scalable electromagnetic wave absorption materials. The research highlights the role of oxygen vacancies in enhancing the dielectric loss and conductivity loss of the nanocomposite, leading to improved electromagnetic wave absorption performance. The study provides a systematic framework for using vacancy engineering to enhance the electromagnetic wave absorption properties of transition metal oxides.