Active participation in social media has been shown to alleviate loneliness and facilitate life satisfaction. Despite the growing presence of older users on short video applications, little is known about how their active engagement on these apps is cultivated. This study aims to explore the underlying mechanisms driving older users’ active participation in short video apps. By integrating the socio-technical approach with attachment theory, we developed a model to examine this behavior. We gathered survey data from 324 older short video users to test our hypotheses, employing Partial least squares structural equation modeling (PLS-SEM) for data analysis. The findings revealed that information and personalization are positively associated with site attachment, and extraversion and network exposure positively influence interpersonal attachment. In turn, site attachment and interpersonal attachment significantly drive older users’ active participation. Our work builds a holistic framework to understand the factors that encourage active participation among older adults in short video apps and also provides practical implications for short video practitioners to serve and engage this important user demographic.