Issues: Opioid overdose kills over 100,000 people each year globally. Mobile health (mHealth) technologies and devices with the capacity to prevent, detect or respond to opioid overdose already exist or could be designed. These technologies may particularly help those who use alone. For technologies to be successful, they must be effective and acceptable to the at-risk population. The aim of this scoping review is to identify published studies on mHealth and wearable technologies that attempt to prevent, detect or respond to opioid overdose.Approach: A systematic scoping review and hand-searching of literature was conducted up to October 2022. APA PsychInfo, Embase, Web of Science and Medline databases were searched. To be included, articles had to report on (i) mHealth technologies that deal with (ii) opioid (iii) overdose.Key Findings: 348 records were identified, with 14 studies eligible for this review across four domains: 1) acceptability/willingness to use overdose-related technologies/devices (five); 2) devices that use biometric data to detect overdose (five); 3) technologies that require intervention/response from others (four); 4) devices that automatically respond to an overdose with administration of an antidote (three).Implications: There are multiple routes in which these technologies may be deployed, but several factors impact acceptability (e.g. discretion or size) and accuracy of detection (e.g. sensitive parameter/threshold with low false positive rate). Conclusion: mHealth technologies for opioid overdose may play a crucial role in responding to the ongoing global opioid crises. This scoping review identifies vital research that will determine the future success of these technologies.