Background: Men face significant health disparities, including higher rates of premature death, mental health challenges, and substance use disorders. Nature-based interventions hold promise for improving men’s health and wellbeing by leveraging natural environments and structured activities aligned with men’s preferences for practical, action-oriented solutions. This realist review explores the contexts, mechanisms, and outcomes of nature-based interventions, providing a gender-specific perspective on how these interventions benefit men.

Methods: A realist synthesis was conducted following Pawson et al.’s iterative framework and the RAMESES reporting standards. Initial programme theories were constructed through early interrogation of the men’s health and greenspace literatures, and expert consultations. Data extraction focused on identifying context-mechanism-outcome configurations to refine programme theories. Analysis involved synthesising findings from qualitative, quantitative, and grey literature to demonstrate how nature-based interventions influence men’s wellbeing.

Results: The review identified nine refined programme theories, encompassing three domains: Being, Doing, and Growing Together. Calming natural settings (PT1) and tailored physical activities (PT2) reduced stress, improved fitness, and enhanced resilience. Purposeful engagement (PT3) and skill development in peer-led, supportive environments (PT4) fostered self-efficacy, identity reformation, and empowerment. Strengths-based, inclusive approaches (PT5, PT6) built social bonds and community cohesion, while structured cognitive engagement (PT7) enhanced problem-solving and collaborative skills. Foundational contexts, including safe, non-judgemental, culturally sensitive spaces (PT8) and tailored, multidisciplinary support (PT9), underpinned these mechanisms, enabling sustained health and wellbeing outcomes.

Conclusions: Nature-based interventions offer a powerful and gender-responsive solution to men’s mental health challenges, combining restorative natural environments, purposeful activities, and peer-led support. Tailored interventions that align with men’s cultural identities and values significantly enhance engagement, self-efficacy, and social cohesion. These findings provide actionable insights for designing inclusive, impactful nature-based interventions, addressing longstanding health disparities. Future research should explore adapting nature-based interventions to diverse populations and contexts to maximise their reach and effectiveness.