M-type Hexaferrites B0.5Sr0.5Fe12−2xNixZrxO19 were synthesized and investigated. The XRD patterns show single phase of the magnetoplumbite barium strontium ferrite and no other phases were present. The samples exhibit well defined crystallization; all of them are hexagonal platelet grains. As the substitution level increased from x = 0.2 to 0.8 mol%, the grains are agglomerated and the average diameter increased. This suggests that Ni–Zr substitution increases the grain size, as observed in the FE-SEM micrographs. The results of magnetic measurement revealed that Ms of barium strontium hexaferrite increased when the value of x increased from 0 to 0.4 mol% and then decreased with the increasing Ni–Zr content. The Hc decreases remarkably with increasing Ni and Zr ions content. Hard magnetic material is converted into soft magnetic material when the substitution level is increased from 0.2 to 0.8 mol%. In particular, Ba0.5Sr0.5Fe12−2xNixZrxO19 with x = 0.2, 0.4, 0.6, 0.8 mol% has suitable magnetic characteristics with particle size small enough for high-density magnetic recording applications.