OBJECTIVES: Evidence regarding interventions to engage men and boys to improve sexual and reproductive health and rights (SRHR) has grown rapidly across subtopics such as HIV, family planning and gender-based violence (GBV). We conducted a review of the effectiveness of interventions to engage men and boys across SRHR domains, lessons learnt about successful programming, and about harms/unintended consequences, in low- and middle-income countries (LMIC). DESIGN: Systematic review of reviews following Cochrane guidelines. DATA SOURCES: PubMed, Cumulative Index to Nursing and Allied Health Literature, Web of Science and Cochrane were searched (18 October-9 November 2022; 9 September 2024). ELIGIBILITY CRITERIA: Eligible reviews were published since 2015, covered WHO-defined SRHR domain(s) and focused mostly on LMIC. DATA EXTRACTION AND SYNTHESIS: Data extraction by multiple reviewers focused on intervention effectiveness, implementation best practices, unintended consequences, and quality/risk of bias. RESULTS: Thirty-five systematic reviews were included, comprising ~960 primary studies. Reviews focused on HIV prevention/care, reproductive health, maternal and newborn health, and GBV. Reviews consistently concluded that men were successfully engaged, yielding benefits to both women and men's SRHR outcomes; no adverse intervention impacts on prevalence of SRHR outcomes were reported. We summarised the interventions most consistently found to be effective across reviews, in a programmer-friendly visual mapped onto a framework of men as clients, partners and agents of change. Person-centred, gender-transformative, multilevel approaches were most effective. Remaining evidence gaps include engaging men as contraceptive , sexually transmitted infections other than HIV, preventing unsafe abortion and SGBV as experienced by men and boys. CONCLUSIONS: There is substantial evidence supporting a range of successful interventions to engage men and boys to improve SRHR, with markedly similar principles and approaches emerging across SRHR domains. It is time to scale up and integrate these strategies, monitoring for any potential harms and tailoring as needed to socio-cultural contexts and for specific vulnerable subpopulations.