Microbial infectious are becoming a global threat, which is a reason for rise in mortality of human beings. One of the reasons for this mortality has been the drug resistance in microbes. The drug resistance poses a major challenge for effective control of microbial infections, and this threat has prompted us to search for alternative strategy to control the microbial infections. Recently, nanomaterials have emerged as an alternative to conventional platforms because they combine multiple mechanisms of action into one platform due to the distinctive properties of nanosized materials. In the present research we have attempted to synthesize ZnO/CdS nanocomposite for its application as an antimicrobial agent. We have characterized the synthesized nanocomposites by X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), photoluminescence spectroscopy (PL), field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM). The nanocomposites have exhibited good antibacterial property against Gram positive and Gram-negative organisms by virtue of the generation of reactive oxygen species (ROS) inside the cells, as reflected by ruptured appearances in the FESEM micrographs. Apart from antimicrobial activity, it also inhibited biofilm formations in Pseudomonas aeruginosa, a causative organism in lung infection and burn associated infections.