Self-regulating temperature-controlled nanoparticles such as Mn-Zn ferrite nanoparticles based magnetic fluid can be a better choice for magnetic fluid hyperthermia because of its controlled regulation of hyperthermia temperature window of 43-45 °C. To test this hypothesis magnetic fluid with said properties was synthesized, and its effect on cervical and breast cancer cell death was studied. We found that the hyperthermia window of 43-45 °C was maintained for one hour at the smallest possible concentration of 0.35 mg/mL without altering the magnetic field applicator parameters. Their hyperthermic effect on HeLa and MCF7 was investigated at the magnetic field of 15.3 kA/m and frequency 330 kHz, which is close to the upper safety limit of 5 * 10 A/m s. We have tested the cytotoxicity of synthesized Mn-Zn ferrite fluid using MTT assay and the results were validated by trypan blue dye exclusion assay that provides the naked eye microscopic view of actual cell death. Since cancer cells tend to resist treatment and show re-growth, we also looked into the effect of multiple sessions hyperthermia using a 24 h window till 72 h using trypan blue assay. The multiple sessions of hyperthermia showed promising results, and it indicated that a minimum of 3 sessions, each of one-hour duration, is required for the complete killing of cancer cells. Moreover, to simulate an in vivo cellular environment, a phantom consisting of magnetic nanoparticles dispersed in 1 and 5% agarose gel was constituted and studied. These results will help to decide the magnetic fluid based hyperthermic therapeutic strategies using temperature-sensitive magnetic fluid.