Solasonine, a steroidal glycoalkaloid isolated from the herbal plant Solanum nigrum Linn., has shown active against multiple human cancers; however, there is little knowledge on the activity of solasonine against gastric cancer until now. This study aimed to examine the effect of solasonine on the biological behaviours of human gastric cancer SGC-7901 cells. The results showed that solasonine suppressed SGC-7901 cell proliferation in a dose-dependent manner. Solasonine treatment mainly induced the cell cycle arrest at G2 phase in SGC-7901 cells. Treatment with solasonine resulted in significant down-regulation of Bcl-2 and Caspase-3 protein expression and reduced Bax and Bcl-xL protein expression in SGC-7901 cells. Solasonine shows a comparable inhibitory effect on the proliferation of human gastric cancer SGC-7901 cells with cisplatin, and solasonine induces of SGC-7901 cell apoptosis through triggering the endoplasmic reticulum stress pathway and the mitochondrial pathway. Our data indicate that solasonine may be a promising agent for the treatment of gastric cancer. © 2022 The Authors. Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.