The silty sand obtained from Waynad, Kerala was found to be liquefaction susceptible under saturated condition when subjected to cyclic loading. The stabilization of the soil using agar biopolymer was found to impart significant resistance to liquefaction since a great reduction in excess pore pressure build-up was observed. In this study, the effect of biopolymer treatment on the secant shear modulus and damping behavior of the soil under varying biopolymer content, curing period and over-consolidation ratio (OCR) have been studied. A set of cyclic triaxial tests were performed on the untreated and biopolymer-treated silty sand. It was observed that the shear modulus increased with increase in the biopolymer content, curing period, and OCR. Furthermore, the biopolymer-treated soil was found to exhibit a higher damping when compared to the untreated silty sand.