Impedance spectroscopy and ac conductivity analysis as a function of temperature have been employed to investigate the conduction mechanism in indiumdoped M-type barium hexaferrite (BaFe_10.5In_1.5O₁₉). Impedance spectra revealed the temperature dependence of dielectric relaxation. The grain and grain boundary contributions to the dielectric properties have been deconvoluted by modeling the Nyquist plot (Z″ vs. Z′) with an equivalent electrical circuit. The ac conductivity was found to follow Jonscher’s power law and the temperaturedependent behavior of critical exponent (s) substantiated the presence of overlapping large polaron tunneling (OLPT) as the underlying conduction mechanism in the investigated temperature regime.