Background: Zinc oxide (ZnO) nanoparticles can induce cytotoxicity by generating reactive oxygen species (ROS), but they are promising in pharmaceutical applications. Metal doping to nanoparticles often mitigates cytotoxicity by altering nanoparticle behavior. This study aims to synthesize nanoparticles of undoped ZnO and ZnO doped with copper, focusing on their diverse biological activities. Methods: The nanoparticles were characterized using various techniques, including energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), scanning electron microscopy (SEM), and fourier-transform infrared (FTIR) spectroscopy. Antibacterial activity was assessed through a modified Kirby Bauer method, while antifungal activity was evaluated using a test-tube dilution method. The anti-termite activity was assessed using established methods with minor modifications. Cytotoxicity on the 3T3 mouse fibroblast cell line was quantified using the methylthiazoletetrazolium (MTT) assay. The mutagenic and carcinogenic potential of the prepared nanoparticles was evaluated using the Ames test. Results: Characterization results confirmed the successful synthesis of ZnO and copper-doped ZnO nanoparticles measuring 1.67 nm and 55.8 nm, respectively. Undoped ZnO displayed antibacterial and antifungal activity against B. subtilis and K. oryzae. Copper-doped ZnO efficiently inhibited the growth of S. marcescens, P. aeruginosa, E. Coli, A. flavus, and K. oryzae. Furthermore, the anti-termite activity of both nanoparticles increased significantly after 48 and 72 hours, resulting in a higher termite mortality rate. The Mutagenic potential of the nanoparticle samples was assessed in two bacterial strains, S. typhimurium TA-98 and TA-100, by observing color changes in the well plates. Purple wells with no color change indicated non-contamination. Zinc oxide was found toxic, with zero positive wells, while copper-doped ZnO showed neither mutagenicity nor toxicity, confirming its safety. Undoped ZnO and copper-doped ZnO nanoparticles exhibited mild cytotoxicity at 30 g/mL concentration, reducing cell viability by 10% and 13%, respectively. However, the cytotoxicity was limited, as evidenced by their 50% growth inhibition (IC₅₀) values, which did not reach concentrations that significantly inhibited cell growth. Conclusion: Both nanoparticles demonstrated antibacterial and antifungal activities, highlighting their potential in pharmaceutical applications, while their anti-termite efficacy suggests applications in pest management. Copper-doped ZnO nanoparticles showed no mutagenicity or cytotoxicity, confirming their safety. At higher concentrations, both nanoparticles displayed mild cytotoxicity. These findings emphasize the adaptability of copper-doped ZnO nanoparticles for various applications in biomedicine and pest control.