Glioma is the most common brain tumor. C6 rat glioblastoma cells provide the possibility to the scientist to study brain cancer. Concanavalin A (Con A) has a lot of antitumoral effects, especially over oxidative stress. In the present study, it was aimed to decide the impacts of various doses of Con A on C6 glioblastoma cells regarding cytotoxicity, thiol/disulfide homeostasis, apoptosis, and inflammation. We detected the cytotoxic activity of Con A (from 7.8 to 500 µg/ml) in C6 cells by utilizing 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide (MTT) and determined the toxic concentration of Con A. Once the optimal doses were found, the thiol–disulfide homeostasis, levels of total antioxidant and oxidant status (TAS and TOS), malondialdehyde (MDA) and glutathione (GSH), pro‐inflammatory cytokines as tumor necrosis factor‐alpha (TNF‐α) and interleukin‐6 (IL‐6), apoptotic proteins as cytochrome c (CYCS), and caspase 3 (CASP3) were measured. Apoptotic and morphological changes in the C6 cells were examined with an inverted microscope and flow cytometry technique. Dose‐dependent Con A triggered oxidative damage in the C6 cells, affecting the inflammatory pathway, so reducing proliferation with apoptotic proteins and morphological changes. But especially, Con A increased disulfide formation by disrupting the thiol/disulfide balance in C6 cells. This study revealed that Con A, known as carbohydrate‐binding protein, generated oxidative damage, inflammation, and apoptosis in a dose‐dependent manner by modulating thiol/disulfide homeostasis in C6 glioblastoma cells.