Long psychiatric hospital stays are unpopular with services users, harmful, and costly. Economic pressures alongside a drive for recovery-orientated care in the least restrictive contexts have led to increasing pressure to discharge people from hospital early. Hospital discharge is, however, complex, stressful, and risky for service users and families. This rapid literature review aimed to assess what is known about early discharge in acute mental health. Searches were conducted in nine bibliographic databases, reference lists, and targeted grey literature sources. Fourteen included papers focused on early discharge in mental health, a population over 18 years with a mental health condition, and reported outcomes on therapeutic care or service delivery. Quality appraisal was undertaken using The Mixed Method Appraisal Tool. The meta-summary of the literature found that early discharge was neither provided to all inpatients nor limited to the Crisis Resolution and Home Treatment (CRHT) service model internationally. Early discharge interventions required collaborative working and discharge planning. It was not associated with unplanned readmissions and had a small effect on length of stay. Most studies reported service outcomes, whereas health outcomes were underreported. Professionals and service users were positive about early discharge and service users asked for peer support. Carers preferred hospital or day hospital care suggesting their need for respite. Limitations in the scope, detail, and quality of the evidence about early discharge leave an unclear picture of the components of early discharge as an intervention, its effectiveness, cost-effectiveness, or outcomes.