In this report, interlinked chitosan-ZnO nanocomposite at 10% ZnO (CZNC-10) is successfully used as green biocide for biofilm control and reduction of biocorrosion on carbon steel material. It was found that 250 $\mu$g/mL CZNC-10 can be used efficiently for the inhibition of sulfate reducing bacteria (SRB) biofilm on carbon steel. The Rct values after 21 and 28 days of incubation in presence of CZNC-10 are almost 3.2 and 2.8 times higher than the control respectively, indicating a strong corrosion inhibition with 74% as maximum inhibition efficiency.