Adolescent parents are at an increased risk for loneliness and mental health challenges compared to childless peers. Nature-based interventions are shown to promote social connectedness. To identify elements of a nature-based intervention to reduce loneliness and foster nature connection among pregnant and parenting adolescents. Sequential exploratory mixed methods. In 2020 and 2021, we piloted the 8-week MINT program at a school for pregnant and parenting teens. Our qualitative approach (n = 17) included online and in-person group meetings with nature-based educational content, discussion, park excursions, mindfulness activities, journaling and nature photography. Subsequently, we recruited 131 young mothers at a children's hospital for a cross-sectional survey based on qualitative school findings. Qualitative results from the school-based intervention showed a preference for meditative and contemplative activities and for spending time in nature with extended family. Participants typically accessed nature close to home. Our clinic-based teen parent survey illustrated that participants' access to nature were most limited by lack of time (25% of responses), company (18%) and energy (28%). While participants showed a close nature connection (mean NR-6 score = 3.9 (SD = 0.84)), they also showed moderate levels of loneliness (mean UCLA Loneliness score = 4.78 (SD = 1.60)). Walking, hiking and/or running were the most preferred nature activity. These findings provide key details to define nature-based activities to address loneliness and psychological well-being among teen mothers. Nature-based health interventions can address loneliness and nature disconnection by building community resilience, improving provider and patient well-being and motivating environmental stewardship. We identify key features of a nature-based intervention for adolescent mothers. These findings support teen mothers in the US and abroad and may serve as a foundation for using nature-based solutions for vulnerable mothers and for adolescents facing loneliness and mental health challenges. No patient or public contribution.