There is mounting evidence suggesting that the effectiveness of positive psychological interventions can be influenced by a variety of factors, including one’s cultural context. Identifying target variables that can effectively serve to improve individual well-being under these boundary conditions is a crucial step when developing viable interventions. To this end, we examined how gratitude disposition, self-esteem, and optimism relate to the subjective (SWB) and psychological well-being (PWB) of Japanese individuals. Multivariate regression analysis revealed that while self-esteem was predominantly more strongly associated with SWB compared to gratitude disposition, the latter was more strongly associated with the PWB dimensions, particularly personal growth, positive relations with others and purpose in life. These results were largely corroborated by a second expanded dataset. In addition, we used experience sampling over a four-week period to examine how momentary affect ratings related to overall daily evaluations. We found that both gratitude disposition and self-esteem moderated the association between momentary positive affect and “good day” evaluations but in opposite ways; increasing gratitude disposition strengthened the association, while increasing self-esteem weakened it. All in all, the current results suggest that while gratitude, self-esteem, and optimism influence individual well-being as a whole, they each likely play distinct roles as enablers of SWB and PWB in the examined cohort.