Temperature is the dominant environmental stimulus that influences the postharvest quality, visual appearance, and nutritional content of fruits. Temperature hastens fruit ripening and senescence by the impact on respiration rate and the acceleration of metabolic reactions. This study was conducted to select the optimized temperature for preserving the quality-related traits and antioxidant potential of cornelian cherry fruits after harvest. The fruits were treated with 1% chitosan and then kept under 0, 5, 10, and 21 °C for 21 days. The results revealed that fruits kept under lower than room temperature (21 °C) better retained antioxidant capacity and had higher levels of phenolics, flavonoids, and anthocyanins and even higher antioxidant enzyme activity, hence attaining prolonged postharvest life. Considering the quantity attributes and the shelf life, the temperature of choice was 0 °C. Zero temperature was also the best to keep the antioxidant capacity of cornelian cherry fruits. Overall, the results showed that low temperature and chitosan pretreatment provide an efficient method for maintaining the nutritional quality and antioxidant capacity of cornelian cherry fruits during storage time.