The number of people presenting to EDs with mental health problems is increasing. To enhance and promote the delivery of safe and efficient healthcare to this group, there is a need to identify evidence-based, best-practice models of care. This scoping review aims to identify and evaluate current research on interventions commenced or delivered in the ED for people presenting with a mental health problem. A systematic search of eight databases using search terms including emergency department, mental health, psyc* and interventions, with additional reference chaining, was undertaken. For included studies, level of evidence was assessed using the NHMRC research guidelines and existing knowledge was synthesised to map key concepts and identify current research gaps. A total of 277 papers met the inclusion criteria. These were grouped thematically into seven domains based on primary intervention type: pharmacological (n = 43), psychological/behavioural (n = 25), triage/assessment/screening (n = 28), educational/informational (n = 12), case management (n = 28), referral/follow up (n = 36) and mixed interventions (n = 105). There was large heterogeneity observed as to the level of evidence within each intervention group. The interventions varied widely from pharmacological to behavioural. Interventions were focused on either staff, patient or institutional process domains. Few interventions focused on multiple domains (n = 64) and/or included the patient's family (n = 1). The effectiveness of interventions varied. There is considerable, yet disconnected, evidence around ED interventions to support people with mental health problems. A lack of integrated, multifaceted, person-centred interventions is an important barrier to providing effective care for this vulnerable population who present to the ED.