The river system of the Bengal delta encompasses a huge amount of fluvial sand; however, no comprehensive studies were available on using this river sand in foundry industries. Hence, the present research evaluates the foundry properties of trans-boundary Brahmaputra River sand and its prospects for use in foundries. Several laboratory analyses have been performed to elicit the foundry properties using standard methods of foundry analysis, including XRD, XRF, TG-DSC, and FESEM. From the study, the sand contains mainly quartz with small amounts of feldspar, amphibole, chlorite, and mica, and exhibits a subangular to subrounded shape. The sand is dominated by SiO2 (67.81–69.97%) and lesser amounts of other oxides, and it is thermally stable within 1000 °C temperature. The grain fineness number (64–79), mineralogical, chemical, thermal, and foundry properties are suitable for non-ferrous metal casting without distortion. Further, the aluminum and zinc alloy casting with trials demonstrate their potential for use in the foundry industries. The outcomes of this study thus offer valuable information about utilizing Brahmaputra River sand for foundry applications.