<p>SnSe is a promising thermoelectric (TE) compound that has attracted increasing attention in recent years, highlighting its advantages in wide temperature range applications. Nanocomposite material engineering provides a straightforward and practical approach to enhance the TE transport performance and mechanical strength of materials. In this study, SiC nanoparticles with varying mass percentages were incorporated into cubic SnSe-based TE materials using the wet ball milling method via mechanical activation (MA). During the rapid hot-pressing sintering (HPS) process, the SiC nanoparticles dispersed at the matrix interface and effectively hindered grains growth owing to the pinning effect. The refined grains and multiple interfaces improved the hole carrier concentration (<i>n</i>) and enhanced the phonon scattering, which collectively optimized the electrical and thermal transport properties of cubic SnSe-based nanocomposites, thereby significantly improving the TE dimensionless figure of merit (<i>ZT</i>). Eventually, the sample with 1.25 wt% SiC achieved the highest <i>ZT</i> of ~ 1.14 at 750&#xa0;K, which was twice that of the uncomposite sample. In terms of mechanical properties, the addition of SiC nanoparticles can effectively enhance the Vickers hardness (<i>H</i>_v) of the material, further demonstrating that this work offers an effective strategy for improving the performance of cubic SnSe-based TE materials.</p> Graphic abstract <p></p>