Lumbar hernia (LH) is a rare abdominal wall hernia that occurs within the anatomic boundaries of the 12th rib, iliac crest, external oblique muscles, erector spinae muscles, and vertebral column. Secondary LH after urological surgery is rare, and the limited evidence hinders consensus on optimal surgical treatment. Here, we present a case of laparoscopic intraperitoneal onlay mesh (IPOM) repair for a large, symptomatic secondary LH after retroperitoneoscopic nephrectomy (RN) with mid-term postoperative outcomes. A 58-year-old man presented with a bulge, pain, and discomfort in the right lumbar area. Three months earlier, he had undergone RN for clear cell carcinoma of the right kidney (pT3aN0M0: stage III). Computed tomography (CT) revealed a right LH with a 10 × 7 cm orifice containing the ascending colon. Considering the symptomatic LH and associated risk of bowel obstruction, laparoscopic surgery was performed eight months after the previous RN. Laparoscopic exploration revealed a 10 (transverse) × 7 (longitudinal) cm defect in the right lateral abdominal wall, with adhesion of the ascending colon. After exposing the hernia orifice, the defect was covered using a composite mesh (Ventralight™ST, BD, Franklin Lakes, NJ, USA). The mesh was trimmed to 16 (transverse) × 13 (longitudinal) cm in size and anchored to the abdominal wall using a single, full-thickness suture. Subsequently, nonabsorbable tacks (CapSure™, BD, Franklin Lakes, NJ, USA) were applied using the double-crown technique. The postoperative course was uneventful, except for the development of a subcutaneous seroma that resolved spontaneously within four months. Follow-up CT performed 36 months after the surgery revealed a slight mesh bulge. However, the patient remained in good physical condition without recurrent symptoms, including a bulge or discomfort. Laparoscopic IPOM repair for secondary LH after RN is safe and effective in alleviating symptoms and preventing recurrence in the mid-term follow-up period. This technique simplifies surgery by avoiding re-dissection of the retroperitoneal space.