In this study, bimetallic (Cu-Mn) substituted M-type Ba1-2xMnxCuxFe12O19 (0.0 <= x <= 0.1) hexaferrites were fabricated via sol-gel auto-combustion route. The effect of bimetallic substitution on structure, morphology and magnetism of BaFe12O19 was studied. Scanning Electron Microscopy confirm images reveal the nanosize of the prepared products with flake morphology. X-ray powder diffraction analysis confirmed their complete conversion to BaFe12O19 hexagonal crystal phase. The results from the magnetic investigations conducted by Vibrating Sample Magnetometer (VSM) and Fe-57 Mossbauer suggested that the saturation magnetization (M-s) and the coercive field of Ba1-2xMnxCuxFe12O19 hexaferrites decrease as the concentration of Cu and Mn increases. The cation distribution calculation showed that the occupancy of Fe3+ ions is increased at 12k and 2b sites with the increase in Cu and Mn substitution.