This study assessed the anti‐biofouling potential of Acalypha indica ethanolic extract against biofouling communities associated with Chembarambakkam Lake water under in vitro conditions. Water samples from the lake were collected at various seasons, and changes in various physicochemical parameters and microbial status were evaluated. Most significantly, the efficacy of the microflora associated with water‐forming biofouling or biofilm network on its susceptibility to the ethanolic extract of A. indica was investigated. Distinct changes were recorded in all the tested physico‐chemical and microbiological statuses in all the seasons. The efficacy of biofouling or biofilm network formation was found to be statistically high during the winter season. Biofouling or biofilm formation was susceptible to the ethanolic extract of A. indica. A. indica treatment brought about notable changes in the morphology of the biofouling networks. A. indica bioactive compounds such as 9,10‐dideutero octadecanal and cyclononasiloxane, octadecamethyl known for their antimicrobial and in vitro properties, effectively prevented biofilm and biofouling formation.