Resveratrol (RSV, 3,5,4′-trihydroxytrans-stilbene) protects sperm from cryo-induced damage in various animal and human species. In this study, we aimed to assess the effect of dog sperm cryoprotective extender containing RSV on the quality of post-thaw dog sperm. Sperm were collected from 4 Beagles and supplemented with different concentrations of RSV (0, 100, 200, and 400 µM). After thawing, apoptosis index, and reactive oxygen species (ROS) levels were assessed to determine post-thaw sperm quality. Dog sperm cryopreserved with 400 µM RSV showed significant improvement in post-thaw sperm quality with lower apoptosis index and ROS levels (p < 0.05). Our results showed that the supplementation of dog sperm cryoprotective extender with RSV at a concentration of 400 µM improved the post-thaw dog sperm quality in the term of sperm ROS production and apoptosis. In addition, we emphasize the necessity of testing the ROS levels and apoptosis index using flow cytometry to determine the quality of post-thaw semen.