Screening of marine macroalgae for quorum sensing inhibitors (QSIs) has gained great interest as they are the potential source of bioactive compounds and reports on QSIs from this source are scanty. Hence, the present study was to explore the QSI potential of the macroalgae to hinder quorum sensing (QS) mechanism of biomarker strains. Among the tested three seaweed extracts, methanolic extracts of G. acerosa was found to hinder QS dependent violacein pigment production in Chromobacterium violaceum (CV 12472) without showing any hindrance effect on bacterial growth. The in vitro quantification assays demonstrated that extract of G. acerosa repressed the violacein production up to 96.5% in C. violaceum CV026 and bioluminescence by 44.7% in Vibrio harveyi by interfering with their respective QS mechanism. Cell viabilities of test strains were not affected in the presence of G. acerosa. The results suggest that the macroalgae G. acerosa is an important source of QSI compounds. Consequently, identification and evaluation of active principle could be explored for prospective biotechnological applications.