[Purpose/significance] With the increasing integration of digital technology, some older adults have devel⁃ oped smartphone dependency. This study explores the antecedents and consequences of smartphone existentially de⁃ pendent behavior among older adults, aiming to provide insights for promoting healthier smartphone use among this population. [Method/process] Data were collected through semi-structured interviews with 27 older adults and 8 fami⁃ ly members of older adults. Grounded theory was employed for coding and analysis. [Result/conclusion] The study es⁃ tablishes the facilitating and restraining mechanisms of smartphone existentially dependent behavior among older adults, highlighting the interplay between promoting and protective factors. Promoting factors include technological pressure, socio-cultural pressure, vulnerability to susceptibility, and emotional anxiety. Protective factors include selfcontrol and digital feedback. Moreover, smartphone existentially dependent behavior among older adults can lead to weakened social connections, intergenerational discord, and decreased sleep quality, further reinforcing their reliance on smartphones.