<p>The present study examined the statistical mediating role of psychological need satisfaction in the relationship between gratitude and life satisfaction across adolescence, young adulthood, and middle adulthood. The study used a cross-sectional correlational design. A total of 1,248 participants volunteered for the study. Of the participants, 306 (24.5%) were adolescents, 321 (25.7%) were young adults, and 621 (49.8%) were middle-aged adults. The Life Satisfaction Scale, Gratitude Scale, and University Students Basic Needs Scale were used as data collection instruments, with the latter used to assess the fulfillment of basic psychological needs across developmental groups. The findings indicated that gratitude was positively associated with life satisfaction and that psychological needs, particularly the Choice Theory dimensions of freedom and fun, showed a partial statistical mediating role in this relationship. The study further demonstrated that developmental stages moderated the association between psychological needs, especially fun and freedom, and life satisfaction. Given the cross-sectional nature of the data, these findings should be interpreted as associative rather than causal. These findings underscore the significance of integrating gratitude and psychological needs within interventions designed to enhance individuals’ life satisfaction.</p>