The ZnTi substituted barium hexaferrite polycrystalline samples have been synthesized by solid-state reaction method. The complex permittivity and permeability measurements are carried out on the BaFe12–2xZnxTixO19 (0.2 ≤ x ≤ 0.6) samples in the microwave frequency range of 8–13 GHz by cavity perturbation technique. The observed abnormal dielectric behavior, i.e., an increasing tendency of dielectric constant with frequency has been attributed to the mixed conduction. The effect of ZnTi substitution on the permittivity and dielectric loss has been investigated in the frequency range of 1 kHz–1 MHz as well. The increase in concentration of ZnTi dopants monotonically increases both the permittivity and the permeability in the investigated frequency ranges, which can be attributed to increased polarizability and unpinning of the domain walls, respectively.