AIM: This systematic review evaluated randomized controlled trials (RCTs) investigating the effectiveness of intra-articular opioid injections for managing temporomandibular joint (TMJ) pain. METHODS: A comprehensive search of indexed databases and Google Scholar was conducted following PRISMA guidelines. Included studies assessed self-reported TMJ pain and maximum mouth opening (MMO) as primary and secondary outcomes, respectively. Risk of bias (RoB) was evaluated using the Cochrane tool, and evidence certainty was rated using the GRADE framework. RESULTS: Ten RCTs met the inclusion criteria, with follow-up periods ranging from 30 minutes to 6 months. Six trials demonstrated significant pain reduction after opioid injections, while one reported no difference following morphine use. Another study found mepivacaine more effective than morphine or saline. Regarding MMO, one trial showed no effect of morphine, whereas two trials found that 1 mg morphine or 1 ml buprenorphine led to greater improvements than 0.1 mg morphine. In three trials, opioids enhanced MMO more than sodium hyaluronate. All studies exhibited low RoB. Certainty of evidence was moderate in six RCTs and low in three. CONCLUSION: There is no credible evidence for the benefit of intra-articular opioid-injections for managing TMJ nociception. PROTOCOL REGISTRATION: www.crd.tork.ac.uk/prospero identified is CRD42024598035.