In this study, silanized-montmorillonite (Si-MMT) reinforced basalt fiber/epoxy composites were prepared and the effect of silanization of MMT on the fatigue and fracture behavior of the composites in seawater condition were analyzed. To compare the properties of Si-MMT/basalt/epoxy (Si-MMT BFRP), Pure basalt/epoxy (pure BFRP) composites were scrutinized in both dry and seawater conditions. The structural changes after silanetreatment were confirmed using TEM, XRD, and FTIR. Further, tensile strength, cyclic loading (fatigue) and fracture properties were studied through the universal testing machine (UTM) and FE-SEM of the fractured surface. It was found that the properties were improved after silanization of MMT due to the better compatibility and dispersion of MMT layers in the matrix. After seawater absorption, debonding occurred due to swelling of the polymer. Hence, deterioration in the properties was observed. However, the composites with Si-MMT still showed better performance among all.