OBJECTIVE: Emergency departments the world over have seen substantial increases in the number of individuals presenting for mental health reasons. However, we have a limited understanding of their experiences of care. The aim of this review was to systematically examine and synthesise literature relating to the experiences of individuals presenting to emergency department for mental health reasons. METHODS: We followed Pluye and Hong's seven-step approach to conducting a systematic mixed studies review. Studies were included if they investigated adult mental health experiences in emergency department from the users' perspective. Studies describing proxy, carer/family or care provider experiences were excluded. RESULTS: Sixteen studies were included. Thematic synthesis identified three themes and associated subthemes. Theme 1 - - comprised: Feeling understood and heard; Engaging in judgement-free interactions; Receiving therapeutic support; Being actively and passively invalidated for presenting to the ED; and Once a psych patient, always a psych patient. Theme 2 - - comprised: Waiting for an 'extremely' long time; and Lacking privacy. Theme 3 was . CONCLUSIONS: The experiences described by individuals presenting to emergency department for mental health reasons were mostly poor. The results illustrate a need for increased mental health education and training for all emergency department staff. Employment of specialist and lived experience workers should also be prioritised to support more therapeutic relationships and emergency department environments. In addition, greater investment in mental health systems is required to manage the current crisis and ensure future sustainability.