The harmful influences of dietary cadmium (Cd) on the chicken kidney and the protective role of selenium (Se) against Cd-induced nephrotoxicity in the chicken are relatively unexplored subjects. The aim of this study was to investigate the ameliorative role of Se on the effects of Cd-induced oxidative stress, endoplasmic reticulum stress, and apoptosis in chicken kidneys. For this study, 100-day-old chickens received Se (as 10 mg Na2SeO3/kg dry weight of diet), Cd (as 150 mg CdCl2/kg dry weight of diet), or Cd + Se in their diets for 60 days. Then, the histopathological changes, Cd and Se contents, levels of oxidative stress, inducible nitric oxide synthase-nitric oxide (iNOS-NO) system activity, levels of endoplasmic reticulum (ER) stress, results of the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay of apoptosis, and expression levels of Bcl-2 and caspase 3 in the kidney were examined. The results showed that Cd exposure caused histopathological and ultrastructural damage and apoptosis of the kidneys. Cd administration significantly increased the accumulation of Cd, the malondialdehyde (MDA) content, NO production, iNOS activity, iNOS expression levels, expression levels of ER stress-related genes (GRP78, GRP94, ATF4, ATF6, and IRE) and the pro-apoptosis gene caspase 3, and the rate of apoptosis. Cd administration markedly decreased the Se content, superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities, and anti-apoptosis gene Bcl-2 expression levels. Co-treatment with Se and Cd obviously reduced the accumulation of Cd, Cd-induced histopathological and ultrastructural changes, oxidative stress, iNOS-NO system activity, ER stress, caspase 3 expression levels, and the rate of apoptosis in the kidneys. These results suggested that Cd exposure caused renal injury and that Se ameliorated Cd-induced nephrotoxicity in chickens.