jats:secjats:titleIntroduction</jats:title>jats:pTransition following discharge from mental health hospital is high risk in terms of relapse, readmission and suicide. Discharge planning supports transition and reduces risk. It is a complex activity involving interacting systemic elements. The codesigning a systemic discharge intervention for inpatient mental health settings (MINDS) study aims to improve the process for people being discharged, their carers/supporters and staff who work in mental health services, by understanding, co-designing and evaluating implementation of a systemic approach to discharge planning.</jats:p></jats:sec>jats:secjats:titleMethods and analysis</jats:title>jats:pThe MINDS study integrates realist research and an engineering-informed systems approach across three stages. Stage 1 applies realist review and evaluation using a systems approach to develop programme theories of discharge planning. Stage 2 uses an Engineering Better Care framework to codesign a novel systemic discharge intervention, which will be subjected to process and economic evaluation in stage 3. The programme theories and resulting care planning approach will be refined throughout the study ready for a future clinical trial. MINDS is co-led by an expert by experience, with researchers with lived experience co-leading each stage.</jats:p></jats:sec>jats:secjats:titleEthics and dissemination</jats:title>jats:pMINDS stage 1 has received ethical approval from Yorkshire & The Humber—Bradford Leeds (Research Ethics Committee (22/YH/0122). Findings from MINDS will be disseminated via high-impact journal publications and conference presentations, including those with service user and mental health professional audiences. We will establish routes to engage with public and service user communities and National Health Service professionals including blogs, podcasts and short videos.</jats:p></jats:sec>jats:secjats:titleTrial registration number</jats:title>jats:pMINDS is funded by the National Institute of Health Research (NIHR 133013)<jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://fundingawards.nihr.ac.uk/award/NIHR133013">https://fundingawards.nihr.ac.uk/award/NIHR133013</jats:ext-link>. The realist review protocol is registered on PROSPERO.</jats:p></jats:sec>jats:secjats:titlePROSPERO registration number</jats:title>jats:pCRD42021293255.</jats:p></jats:sec>