Squamous cell carcinoma (SCC) of the maxillary sinus is a rare malignancy that often presents at an advanced stage due to its nonspecific symptoms and anatomical complexity. Surgical resection remains the primary treatment, frequently combined with radiotherapy and/or chemotherapy. However, in selected patients, non-surgical alternatives may be necessary due to comorbidities or personal preference. We report the case of a 46-year-old male with a history of pharmacologically managed hypertension who presented with progressive left ocular discomfort, erythema, and epiphora. Imaging revealed a mass occupying the left maxillary sinus with regional extension. Histopathological analysis confirmed SCC. Although extensive surgical resection was recommended, the patient declined surgery and chemotherapy due to concerns about functional and cosmetic outcomes. As an alternative, he underwent stereotactic radiosurgery using the ZAP-X system. The treatment delivered a total of 27 Gy in three fractions with conformal dose distribution and strict organ-at-risk sparing. Follow-up over 12 months demonstrated sustained clinical improvement and radiological evidence of complete response, without evidence of local recurrence or distant metastasis. While surgery followed by adjuvant therapy is the gold standard for maxillary sinus SCC, this case supports the potential role of stereotactic radiosurgery as a viable, organ-preserving alternative in early-stage disease when surgery is not feasible or preferred. A review of the literature indicates limited data on non-surgical management for early-stage SCC, particularly using stereotactic radiosurgery systems like ZAP-X. This case is the first reported instance of early-stage (T2N0M0) maxillary sinus SCC successfully managed with stereotactic radiosurgery alone, demonstrating favorable clinical and imaging outcomes after one year. This treatment strategy may offer a promising alternative in well-selected cases, warranting further research into its broader applicability.