Hot brine stretching of Mozzarella cheese can lead to the loss of protein and other components, while whey, which is rich in nutrients such as whey protein, has an important influence on the protein structure and functional characteristics of cheese. In this study, the effects of different stretching temperatures (65, 75, 85, and 95 ℃) in whey on the physiochemical and textural characteristics of Mozzarella cheese were investigated by using brine at 95 ℃ as a control. The results showed that the yield of stretched cheese in whey at 75 ℃ was as high as 7.38%, which was significantly higher than that of the other treatments (P < 0.05), and the cheese had good texture characteristics. In contrast, the stretched cheese in whey at 85 ℃ had the best sensory quality. Scanning electron microscopy analysis showed that at 75 ℃, the protein cross-linking was moderate and the cheese had an ideal balance of elasticity and hardness. Through sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis, it was found that stretching in whey at 75 ℃ more effectively retained the protein components in cheese. Additionally, rheological analysis indicated that the cheese subjected to hot stretching in whey exhibited better elastic properties.