This study is the first to apply terror management theory to understanding smartphone addiction by examining the potential indirect effect of death anxiety on smartphone addiction via inclusion of smartphone in the self (i.e., self-expansion), affiliation motivation (the desire to connect with others) for emotional support, and smartphone use. The sample consisted of 1483 Chinese university students between the ages of 18 and 24 (M = 19.14, SD = 1.03) who voluntarily completed an anonymous questionnaire survey. As hypothesized, death anxiety, inclusion of smartphone in the self, affiliation motivation, and smartphone use were directly, positively correlated with smartphone addiction. In addition, death anxiety exerted significant indirect effects via various pathways, including (i) affiliation motivation for emotional support and smartphone use and (ii) inclusion of smartphone in the self and smartphone use. Findings suggest that effective interventions for smartphone addiction should include targeting death anxiety, self-expansion, and affiliation need frustration.