Magnetic–dielectric composites are usually designed to develop high-performance microwave absorbers. In this paper, magnetic–dielectric Ti 3 SiC 2 /Co 2 Z ferrite composites were firstly prepared for application in microwave-absorbing materials. The phase structure, micro-morphology, electromagnetic response behavior, and microwave absorption performance of these composites have been investigated and subsequently discussed. The measured results showed that the introduction of dielectric Ti 3 SiC 2 into magnetic Co 2 Z ferrite can increase the complex permittivity and dielectric loss of these composites appropriately. And then, a desired stronger reflection loss peak of –38.04 dB could be achieved with a thin thickness of 1.5 mm in the Ti 3 SiC 2 /Co 2 Z composite-filled microwave-absorbing materials. It was also found that appropriately increasing the complex permittivity can improve the electromagnetic attenuation ability and the impedance-matching property simultaneously, which eventually contributes to the enhanced microwave absorption performance.