Background: Subarachnoid block is widely utilized for lower abdominal and limb surgeries due to its rapid onset, effective blockade, and minimal side effects. Bupivacaine traditionally dominates as the primary agent, but the exploration of adjuvants such as nalbuphine has shown a considerable promise in improving analgesia and anaesthesia. Nalbuphine, a semi-synthetic opioid, with its unique pharmacological profile, is positioned as a potential intrathecal adjuvant. However, its efficacy varies, necessitating an evaluation of its effectiveness at moderate doses in conjunction with hyperbaric bupivacaine for lower abdominal surgeries. Methodology: In the present hospital based observational study, 90 patients undergoing lower abdominal surgeries were enrolled. Patients were randomly assigned to three groups, each receiving a different intrathecal formulation. Group A received bupivacaine alone, while Group B & C received nalbuphine as adjuvants in dosage of 0.6mg and 0.8mg respectively. Sensory and motor blocks were assessed using pinprick and the Bromage scale, respectively. Groups were compared for onset, duration, and adverse effects. Results: The study found that the duration of sensory and motor blocks in groups B and C was significantly prolonged compared to group A, p<0.05. Duration of anesthesia also progressively increased from A to C (p<0.05). While there were no clinically significant differences in hemodynamics; hypotension and bradycardia, nausea and vomiting were more observed in nalbuphine groups with higher doses. Conclusion: Intrathecal nalbuphine demonstrated a substantial prolongation of sensory and motor block durations, suggesting its potential for enhanced postoperative analgesia in lower abdominal surgeries. The study underscores the utility of nalbuphine in subarachnoid blocks, emphasizing the need for careful monitoring and consideration of observed hypotension. Further research with larger cohorts is crucial to validate these findings and optimize the intrathecal nalbuphine dose for improved clinical outcomes.