Sexual behavior of psychiatric inpatients is often inadequately addressed within psychiatric institutions. This systematic review aimed to identify existing policies, guidelines, and recommendations regarding inpatient sexual behavior in psychiatric units, institutions, and supported housing across Europe in existing literature. It also aimed to assess the attitudes held by mental health professionals (MHPs) and inpatients toward existing policies, guidelines, and recommendations. Nine databases were searched in seven languages for articles published between 2000 and 2020. Double-blind bias assessment was performed on 10 articles. Five thematic categories emerged from the selected studies: (1) types of policies and guidelines; (2) MHPs' and inpatients' attitudes toward inpatient sexual behavior; (3) impact and strategies related to inpatient sexual behavior; (4) barriers to inpatient sexual behavior; and (5) facilitators to inpatient sexual behavior. Most screened publications reported implicit norms addressing inpatient sexual behavior among the staff. Surveyed MHPs and inpatients typically showed opposing attitudes regarding inpatient sexual behavior, with MHPs generally deeming such behavior unsafe and inpatients emphasizing it as their human right. The aims of this systematic review were partially fulfilled as articles reported little or no policy documents and guidelines and, therefore, did not allow for the assessment of policy impact. MHPs' attitudes toward inpatient sexual behavior were addressed and trends in several countries outside of Europe addressing inpatient sexual behavior were discussed. Finally, capacity to consent with respect to inpatient sexual behavior is discussed in the context of human rights.