Mechanical restraint is a commonly used restrictive practice worldwide, although reducing its use is an international priority. Interventions to reduce mechanical restraint are needed if reducing mechanical restraint is to succeed. Therefore, this systematic review aimed to examine evaluated evidence‐based interventions that seek to reduce the incidence of and/or time in mechanical restraint in adult mental health inpatient settings. The JBI framework was used to guide this systematic review. The search strategy included peer‐reviewed primary research literature published between 1999 and 2023. Two authors independently conducted the systematic search, selection process and data extraction process. Forty‐one studies were included in this review. Using content analysis, we grouped interventions into four categories: (I) calm‐down methods, (II) staff resources, (III) legal and policy changes and (IV) changing staff culture. Interventions to reduce mechanical restraint in adult mental health inpatient settings have shown some promise. Evidence suggests that a range of interventions can reduce the incidence of and/or time in mechanical restraint. However, controlled trials were lacking and consensus was lacking across studies. Furthermore, specific findings varied widely, and reporting was inconsistent, hampering the development of interventions for this issue. Further research is needed to strengthen the evidence base for reducing mechanical restraint in mental health inpatient settings.