The combination of two dielectric-magnetic components in the same composite has been shown to significantly improve the effectiveness of electromagnetic (EM) shielding and microwave absorption (MWA) because they have both a combination of high dielectric and magnetic losses and good impedance matching. The novel Bi 1/2 (Na 0.8 K 0.2 ) 1/2 TiO 3 /Fe 3 O 4 (BNKT/Fe 3 O 4 ) composite has been successfully synthesized by a two-step method with wide effective absorption bandwidth (EAB = 16 GHz) in the high-frequency (2-18 GHz). It was evident that the MWA efficiency of the BNKT/Fe 3 O 4 composite has been significantly improved compared with pure Bi 1/2 (Na 0.8 K 0.2 ) 1/2 TiO 3 or Fe 3 O 4 materials. In addition, the BNKT/Fe 3 O 4 composite could achieve reflection loss (RL = ¹39.41 dB, ³99.99% at 10.16 GHz) with a sample thickness optimal (d = 4.7 mm). This work shows that the novel BNKT/Fe 3 O 4 composite has excellent MWA properties, all contributing to a potential candidate in the electromagnetic wave absorption and shielding fields.