Aim: This study aimed to assess the effects of mindfulness practices conducted in natural settings on the mental health, emotional regulation, and attentional focus of young children (ages 6-15) and their teachers in Greece, Cyprus, and Portugal. Materials and Methods: A mixed-methods design was employed, combining quantitative data from the MiNa (Mindfulness in Nature) scale with 673 children and 220 adults as well as qualitative interviews with 20 children and 20 teachers across the three countries. Quantitative data was analyzed using descriptive statistics and paired t-tests to measure pre- and post-intervention changes, while qualitative data was examined through thematic analysis to capture nuanced experiences and perceptions. Results: Findings revealed significant improvements in emotional awareness, attentional focus, and stress reduction for both children and teachers. Children reported higher levels of emotional regulation and connection to their surroundings, while teachers experienced reduced stress and enhanced classroom dynamics. Cross-cultural comparisons indicated that nature-based mindfulness practices provided universal benefits, though participants from all countries Greece, Portugal and Cyprus. Conclusions: Nature-based mindfulness interventions demonstrate promising outcomes in promoting emotional well-being, cognitive focus, and stress resilience for young children and adults. The findings underscore the potential of integrating mindfulness in nature into early childhood education as a holistic approach adaptable to diverse cultural and environmental contexts.