Sixty-four adults scheduled for unilateral total hip arthroplasty (THA) were randomized to receive either quadro-iliac plane block (QIPB) plus multimodal analgesia (Group Q) or multimodal analgesia alone (Group C). All patients received spinal anesthesia with 0.5% bupivacaine and postoperative IV paracetamol and dexketoprofen. Group Q additionally received a unilateral ultrasound-guided QIPB in the post-anaesthesia care unit (PACU) using 40 mL 0.25% bupivacaine. Outcomes were measured by blinded assessors. The primary outcome was the quality of recovery (QoR-15) score at 24 hours. Secondary outcomes included pain scores at rest and movement, tramadol rescue use, time to first analgesic request, incidence of postoperative nausea and vomiting (PONV), antiemetic use, and patient satisfaction. Overall, the results demonstrated that QIPB significantly improved QoR-15 and all subdomains, lowered pain scores at all time points, eliminated opioid consumption in most patients, prolonged time to first analgesic request, reduced nausea and antiemetic use, and improved patient satisfaction. These findings indicate QIPB is an effective analgesic adjunct after THA.