The aim of the present study was to investigate the in vitro cytotoxicity of PEGylated Mn doped ZnO nanoparticles against the Human Cervical Cancer HeLa Cells. Pure and Mn (2.0, 2.5 and 3.0%) doped ZnO nanoparticles were synthesized by chemical precipitation method. The structural and morphological interpretations of the as prepared nanoparticles were carried out using X-Ray Diffraction (XRD), UV-Vis DRS Spectroscopy, Photoluminescence Spectra and Field Emission Scanning Electron Microscopy (FESEM) techniques. The cytotoxicity mechanisms of the as prepared nanoparticles were investigated against the Human Cervical Cancer HeLa Cells by observing the cell penetration ratio, cell viability and ROS generation. It was observed that, among the four nanoparticles (znsp1, znsp2, znsp3 and znsp4) 2.0% Mn doped ZnO nanoparticles exhibited higher cell killing activity. The cytotoxicity results showed that pure and Mn doped ZnO nanoparticles exert distinctive killing effects on Human Cervical Cancer HeLa Cells while posing minimal impact on normal cells.