The objective of this study was to assess the effectiveness of nonpharmacological interventions in enhancing the mental health and psychosocial outcomes of parents who have experienced perinatal loss, in comparison to active/inactive control groups. It also sought to identify the characteristics and components of effective interventions in the included studies. A comprehensive search was conducted across seven databases from January 2008 to December 2023. The analysis included randomized controlled trials (RCTs) published in English journals and dissertations that reported at least one mental health outcome postintervention for parents with perinatal loss. Twenty-one RCTs were included. The findings demonstrated significant improvements of nonpharmacological interventions in the grief, posttraumatic stress disorder, depression, anxiety, and perceived social support of parents with perinatal loss, with moderate-to-high certainty of evidence. Optimal characteristics of nonpharmacological interventions for parents with perinatal loss were identified to inform future studies, including the intervention approaches (cognitive-based interventions), delivery modalities (face-to-face), and formats (individual-based), and a recommended number of sessions of four or fewer. To validate these findings and explore the process of nonpharmacological interventions in improving health outcomes for parents with perinatal loss from diverse backgrounds, further rigorous RCTs with larger sample sizes and longer follow-up periods are required.