Rapid urbanization in Iran’s metropolises, particularly in dense residential complexes such as Tehran’s Ekbatan Town, has resulted in social isolation, weakened intergenerational bonds, and mental health challenges. This study aimed to investigate the role of spontaneous community gardens as a low-cost tool for enhancing psychological well-being and generational cohesion, providing policy implications for sustainable urban planning. A mixed-methods (quantitative-qualitative) approach was employed, with the study population consisting of active residents in Ekbatan’s community gardens. A standard questionnaire (including the WHO-5 scale, 9 Likert items, and open-ended questions) was distributed among 88 participants (selected via purposive-snowball sampling). Instrument reliability was confirmed with Cronbach’s alpha coefficients of 0.91 and 0.85. Data were analyzed using SPSS (descriptive statistics, Pearson correlation, t-test) and thematic analysis. Findings indicated an average mental well-being score of 19.12 out of 25 and an intergenerational bonds score of 3.83 out of 5. The highest score belonged to "feeling useful through mutual learning" (4.33). Age group differences were not significant (p > 0.05), but a significant positive correlation was observed between weekly activity hours and both variables (r ≈ 0.30, p < 0.01). Qualitative analysis highlighted the main themes of "tranquility derived from connection with nature," "intergenerational mutual learning," and "strengthened citizen collaboration." These gardens can be integrated into urban regeneration policies and social health programs, shifting the planning paradigm from merely providing green space towards creating opportunities for participation within it.