Sarcoptic mange is a highly contagious and often lethal parasitic skin disease caused by the mite Sarcoptes scabiei, which is frequently reported in red foxes (Vulpes vulpes). However, there is a lack of documented cases and treatment strategies for sarcoptic mange in reintroduced red fox populations, particularly in South Korea. This study describes 27 cases of sarcoptic mange outbreaks in 26 red foxes reintroduced into South Korea between 2019 and 2024. Of these, 15 foxes were rescued alive, while 12 were found dead. Blood tests of the surviving animals (n = 15) showed significant leukocytosis, anemia, decreased albumin levels, increased globulin levels, elevated blood urea nitrogen levels, and decreased creatinine levels, indicative of a chronic wasting infection. Treatment with ivermectin or fluralaner resulted in complete recovery in 12 of 15 animals, while three animals died during treatment. Necropsy of the deceased animals (n = 12) revealed characteristic skin lesions, such as alopecia, hyperkeratosis, epidermal hyperplasia, and dermatitis. The study findings highlight the importance of long-term monitoring and active, continuous treatment of sarcoptic mange, a major threat, for the stable re-establishment of reintroduced foxes in South Korea.