Optimization of manganese-substituted iron oxide nanoferrites having the composition Mn x Fe 1−x Fe 2 O 4 (x = 0−1) has been achieved by the chemical coprecipitation method. The crystallite size and phase purity were analyzed from X-ray diffraction. With increases in Mn 2+ concentration, the crystallite size varies from 5.78 to 9.94 nm. Transmission electron microscopy (TEM) analysis depicted particle sizes ranging from 10 ± 0.2 to 13 ± 0.2 nm with increasing Mn 2+ substitution. The magnetization (M s ) value varies significantly with increasing Mn 2+ substitution. The variation in the magnetic properties may be attributed to the substitution of Fe 2+ ions by Mn 2+ ions inducing a change in the superexchange interaction between the A and B sublattices. The self-heating characteristics of Mn x Fe 1−x Fe 2 O 4 (x = 0−1) nanoparticles (NPs) in an AC magnetic field are evaluated by specific absorption rate (SAR) and intrinsic loss power, both of which are presented with varying NP composition, NP concentration, and field amplitudes. Mn 0.75 Fe 0.25 Fe 2 O 4 exhibited superior induction heating properties in terms of a SAR of 153.76 W/g. This superior value of SAR with an optimized Mn 2+ content is presented in correlation with the cation distribution of Mn 2+ in the A or B position in the Fe 3 O 4 structure and enhancement in magnetic saturation. These optimized Mn 0.75 Fe 0.25 Fe 2 O 4 NPs can be used as a promising candidate for hyperthermia applications.