Background: Intrathecal adjuvants are frequently used with hyperbaric bupivacaine to enhance the quality and duration of spinal anesthesia in lower limb surgeries. Fentanyl and Nalbuphine are commonly used opioids, but their comparative efficacy and safety profiles remain underexplored. The aim is to compare the effects of intrathecal Nalbuphine and Fentanyl as adjuvants to hyperbaric bupivacaine on sensory and motor block characteristics, hemodynamic stability, perioperative adverse events, postoperative analgesia, and patient satisfaction in elective lower limb surgeries. Materials and Methods: Eighty adult patients undergoing elective lower limb surgeries under spinal anesthesia were randomized into two groups of 40 each. Group N received 3 mL of 0.5% hyperbaric bupivacaine with 1 mg Nalbuphine, and Group F received 3 mL of 0.5% hyperbaric bupivacaine with 25 µg Fentanyl intrathecally. Sensory and motor block characteristics, hemodynamic parameters, perioperative adverse events, time to first mobilization, analgesic requirements, pain scores (VAS), and patient satisfaction were assessed. Results: Fentanyl produced a significantly faster onset of sensory and motor block but shorter duration of both compared to Nalbuphine. Nalbuphine provided longer-lasting analgesia, lower postoperative pain scores, reduced analgesic consumption, and higher patient satisfaction. Hemodynamic changes were comparable between groups, though Fentanyl showed slightly greater numerical decreases in blood pressure and heart rate. Pruritus and nausea/vomiting were more frequent with Fentanyl. Conclusion: Both adjuvants effectively enhance spinal anesthesia. Fentanyl offers rapid onset, whereas Nalbuphine provides a more balanced perioperative profile, with prolonged analgesia, fewer adverse events, stable hemodynamics, and improved patient satisfaction, making it a favorable choice for lower limb surgeries. Keywords: Analgesia, Fentanyl, Nalbuphine, Spinal Anesthesia, Sensory Block, Motor