The present study aimed to investigate the effects and mechanisms of STAM binding protein-like 1 (STAMBPL1) knockdown in the suppression of gastric cancer activities. Pathological data and STAMBPL1 protein expression were analysed in 36 patients with gastric cancer, including 24 stage I–II and 12 stage III–IV patients, by haematoxylin and eosin staining and immunohistochemistry. In vitro cell experiments were performed to measure AGS cell proliferation, apoptosis, invasion and migration by MTT, Celigo cell count, flow cytometry, Transwell and wound healing assays following STAMBPL1 knockdown. The relative protein expression levels were evaluated by western blotting. When compared with the adjacent normal tissues, STAMBPL1 protein expression in the gastric cancer tissues with increasing stages was significantly upregulated (P<0.01 or P<0.001). STAMBPL1 gene expression was not identified to be significantly different between AGS and MGC80-3 gastric cancer cells (P>0.05). Following STAMBPL1 knockdown by short hairpin RNA (sh)STAMBPL1, cell proliferation was significantly suppressed, the cell apoptosis rate was significantly upregulated, and the numbers of invasive AGS cells and the AGS wound healing rate were significantly decreased (P<0.01 and P<0.001, respectively), compared with those in the shControl group. Additionally, STAMBPL1 and NF-κB protein expression levels were significantly downregulated in the shSTAMBPL1 group (P<0.001, respectively). STAMBPL1 may be oncogenic in gastric cancer, and STAMBPL1 knockdown may suppress gastric cancer development.