In this work, a systematic study of structural, optical, magnetic and antibacterial properties of Mn doped ZnO has been investigated. Zinc oxide (ZnO) and Mn2+ doped zinc oxide (ZnMnO) nanoparticles (NPs) were prepared through co-precipitation method. The X-ray diffraction studies confirmed that the synthesize nanoparticles did not modify the crystal structure upon Mn doping, but the microstructural parameters were changed considerably while increasing the concentration of Mn dopant. The HRTEM images showed that the ZnO NPs were exhibited nanospheres like morphology and a reduction in the average particle size from 41 nm to 33 nm were observed upon Mn2+ doping. The elemental composition of Zn, Mn and O atoms were identified by EDAX spectra. The Zn-O stretching bands were observed at 539 and 525cm-1 in the FTIR spectra and, the zinc and oxygen vacancies defects were confirmed by PL spectra. From the UV-Vis spectra, the band gap was estimated as 2.7 eV for pure and 2.9 eV for Mn doped ZnO NPs. The Mn doped ZnO NPs showed greater antibacterial effect than the pure ZnO NPs. The magnetization measurements for Mn doped ZnO samples under room temperature ferromagnetism (RTFM) showed the ferromagnetic phase that could originated from the interactions between Mn2+ ions and oxygen vacancies and the defects incorporated in the ZnO matrix.