Sweat gland carcinoma (SGC) is a rare type of malignant adnexal tumours of the skin (MATS). It has potential for local infiltration, regional nodal involvement, and distant metastasis. Wide local excision with regional lymph nodal dissection is the mainstay of treatment and there are no consensus guidelines for adjuvant treatment. We present a case report of a gentleman, suffering from SGC in the left lumbar region with axillary nodal metastasis, presenting with a longstanding skin nodule, with recent spurt in growth and ulceration over it. He was treated with wide local excision of the lesion and left axillary nodal dissection. Postoperative histopathology and immunohistochemistry confirmed the diagnosis of SGC. He received adjuvant radiotherapy to primary and nodal sites due to the presence of high-risk features. Diagnosis of SGC is very challenging due to clinical variation, nonspecific immunohistochemistry profile, and histopathological surprises. Due to the paucity of relevant literature, the role of adjuvant radiotherapy is still not established, but in view of the aggressive behaviour of SGC, radiotherapy significantly improves local and regional control, particularly in the presence of high-risk pathological features. Further studies in the domain of adjuvant treatment of SGC is needed to improve disease outcomes optimally.