There is uncertainty related to the prescribing of opioid analgesics to treat chronic pain in adult patients with opioid use disorder (OUD) or a history of OUD. Guidance is required on the optimal prescribing of opioid analgesics to ensure that patients are benefiting from treatment with minimal harm. This systematic review examined 5 observational studies on the safety of opioid analgesics alone or with opioid agonist therapy for chronic pain in patients with OUD or a history of OUD. No evidence was found regarding the efficacy of opioid analgesics for managing chronic pain in these patients. Low certainty evidence suggests a reduced risk of fatal opioid-related toxicity for those receiving both treatments compared to opioid analgesics alone. Uncertainty remains about the impact on toxicity risks, prolonged opioid use, and opioid analgesic dosage or frequency. Further research is needed, especially for Indigenous and equity-deserving populations.