Despite the growing prevalence of social media usage among older adults, the impact for their well-being remains unclear. This study investigates the impact of social grooming on social media (SGSM) on the life satisfaction of a representative sample (N = 591) of older adults (aged 55 and above) in Taiwan. Using an indirect effects paradigm, the study examines the mediation mechanisms of bridging social capital and perceived social support in the relationship between SGSM and life satisfaction. Additionally, the moderating effect of social network size (SNS) is assessed. The results indicate that bridging social capital and social support fully and sequentially mediate the influence of SGSM on older adults’ life satisfaction. Furthermore, SNS is identified as a significant moderator in this sequential mediating effect. These findings contribute to the existing literature on social media use and highlight the importance of understanding the impact of SGSM on life satisfaction and other psychological outcomes for older adults. The results also emphasize the need to consider the unique characteristics and specific needs of older adults, and to promote and assist them in effectively using social media to expand their social networks and acquire social support, which are crucial for their life satisfaction.