Background: The research aimed to assess how fentanyl and dexmedetomidine impact Ropivacaine in supraclavicular brachial plexus blocks regarding pain relief, motor block duration, and onset times for sensory and motor blocks. Methods: This prospective comparative study involved 70 patients (aged 18-60, ASA 1 or 2) undergoing upper limb orthopaedic surgeries at the Department of Anesthesiology, Dr. M.K. Shah Medical College, Ahmedabad, Gujarat, India. It was conducted from January 2023 to December 2023 after participant consent. Results: Significant differences were observed in sensory block onset times: 6.42 ± 1.21 min for dexmedetomidine vs. 10.04 ± 1.24 min for fentanyl. Motor block onset times were also significant: 9.8 ± 0.96 min (dexmedetomidine) vs. 12.90 ± 1.80 min (fentanyl). Duration of motor block was longer with dexmedetomidine (527 ± 48.01 min) than fentanyl (459 ± 34.73 min). Sensory block duration was also longer with dexmedetomidine (538.66 ± 48.5 min) compared to fentanyl (487.32 ± 48.27 min). Dexmedetomidine provided prolonged analgesia (734.1 ± 34.30 min) compared to fentanyl (650.1 ± 23.33 min). Conclusion: The addition of dexmedetomidine to 0.5% Ropivacaine in supraclavicular brachial plexus block significantly hastens the onset of sensory and motor blocks, prolongs their duration, and extends analgesia compared to fentanyl combined with 0.5% Ropivacaine.