<p>Nanowire composites have attracted much interest recently owing to the experimental demonstrations of many tempting potential applications based on the excellent electrical, thermal and mechanical properties. The critical role of interfacial resistance in nanowire composites has long been recognized, as evidenced by experimental studies dating back several decades showing its dependence on filler size and contact density. While the importance of these effects is well established, many modeling approaches still simplify the problem by assuming ideal nanowire contacts or treating interface resistance through empirical corrections. In this study, we propose a physically consistent model that incorporates interfacial electrical and thermal resistances based on transport physics at nanoscale junctions, and examine their influence on percolation-driven transport. In this study, we develop a physics-based framework that explicitly models interfacial electrical and thermal resistances and reveals their critical role in percolation-controlled transport. However, in the present study, we show that calculated electrical and thermal conductivities are orders of magnitude higher than experimental results when interfacial resistances are ignored. These resistances are not purely contact resistances but stem from rough nanowire junctions, suppressed tunneling, and local potential barriers. By modeling these effects through a square potential barrier approach, we introduced interfacial resistances into the calculations, we find the obtained electrical and thermal conductivities match well with experiments in a wide range of nanowire concentration. Our study evaluated and modeled the effect of interfacial thermal resistance in nanowire composites, and the results demonstrated a dominant role of interfaces on electrical and thermal properties.</p>