This study addresses a significant knowledge gap in the literature by examining the relationship between religious involvement and subjective wellbeing (SWB) among older adults in Taiwan, a cultural context that has been underrepresented in existing research, with a focus on gender and age differences. Using data collected in Taichung City in 2017 (N = 645), this study measured religious involvement through religious affiliation, religiosity and frequency of religious participation, and assessed SWB via life satisfaction and happiness. Findings revealed no significant association between religious involvement and life satisfaction. However, religious participation was positively correlated with happiness. Gender differences were observed: Buddhism and Taoism were positively associated with life satisfaction among males, whereas religiosity and religious participation were significantly related to life satisfaction and happiness among females. Age disparities were also found, with religiosity significantly relating to both life satisfaction and happiness in the old-old group (70–89 years) but not in the young-old group (60–69 years). These findings highlight the nuanced associations between religious involvement and SWB, emphasising the importance of considering gender and age variations in future research. Future studies should further explore the cultural contexts that shape these relationships and examine other potential mediating factors to provide a more comprehensive understanding of how religious involvement influences wellbeing across different demographic groups.