This assessor-blinded randomized clinical trial assessed 300 patients undergoing primary arthroscopic anterior cruciate ligament (ACL) reconstruction were randomized to receive either periarticular injection (PAI) or no periarticular injection (nPAI). After losses to follow-up related to COVID-19 infection, 288 patients were included in the final analysis, with 142 patients in the PAI group and 146 patients in the nPAI group. All procedures were performed under spinal anesthesia using hamstring tendon autograft with standardized surgical and rehabilitation protocols. The primary outcomes were postoperative pain measured using visual analog scale scores and cumulative opioid consumption expressed as morphine milligram equivalents. Secondary outcomes included narcotic-related adverse events and patient satisfaction. Outcomes were assessed in the postoperative acute care unit and at 4, 8, and 24 hours, 2 days, and before discharge, with adverse events tracked to 2 weeks. Overall, the results of the study revealed that intraoperative periarticular injection significantly reduced early postoperative pain scores and opioid consumption compared with no periarticular injection, with a higher proportion of patients achieving clinically meaningful pain relief at 24 hours and fewer narcotic-related adverse events.