A sialo-cutaneous fistula is a communication between the skin and a salivary gland or duct discharging saliva. Trauma and iatrogenic complications are the most common causes of this condition. Treatments include aspiration, compression, and the administration of systemic anticholinergics; however, their effects are transient and unsatisfactory in most cases. We had a case of a patient who developed an iatrogenic sialo-cutaneous fistula after wide excision of squamous cell carcinoma in the parotid region that was not treated with conventional management, but instead completely resolved with the injection of botulinum toxin. Based on our experience, we recommend the injection of botulinum toxin into the salivary glands, especially the parotid gland, as a conservative treatment option for sialo-cutaneous fistula.