Background: Carer criticism, of all expressed emotion (EE) elements, has been linked most consistently with poorer clinical outcomes for patients transdiagnostically. Patient perception of carer criticism (perceived criticism) has been found to predict poorer outcomes across several disorders. The Perceived Criticism Measure (PCM) has featured predominantly in the literature. Despite the bidirectional effects of caregiving relationships on patient and caregiver outcomes,to date, there are no systematic reviews investigating the role of perceived criticism (PC) in both patient and carer outcomes in severe mental health conditions. Objectives: This review aimed to systematically synthesise the evidence available in relation to the role of PC in patient and carer outcomes in severe mental disorders as well as bridge the gap in current knowledge of existing PC measures. Method: A systematic review (Prospero ID: CRD42019122820) was conducted in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Four databases (EMBASE, Medline and PsycINFO through OVIDSP and Web of Science) were searched, identifying literature focusing on the role of PC in patient and carer outcomes across severe mental disorders. For the purpose of this review, schizophrenia and related disorders, non-organic psychosis, bipolar disorder, anxiety disorders (including panic disorder, obsessive compulsive disorder, post-traumatic stress disorder, generalised anxiety disorder, social anxiety disorder or agoraphobia), eating disorders (including anorexia, bulimia or binge eating disorder) and depression were included under the severe mental illness (SMI) umbrella. The quality of the reviewed studies was evaluated using an adapted version of the “Quality Assessment Tool for Quantitative Studies” developed by the Effective Public Health Practice Project (EPHPP).