BACKGROUND: Increasing observation and evidence suggest that the process of digitalization could have profound impact to the development of human mind and self, with potential mental health consequences. Self-differentiation is important in human identity and self-concept formation, which is believed to be involved in the process of digitalization. OBJECTIVE: This study aimed to investigate the relationship between digitalization and personal attributes in the actual selves in the physical and virtual worlds. METHODS: A community cohort of 397 participants aged 15 to 24 years old was recruited consecutively over about 3 months. Assessment was conducted upon the indicators of digitalization (smartphone use time, leisure online time, and age of first smartphone ownership), smartphone addiction, 14 selected personal attributes in the actual selves in the physical and virtual worlds, psychiatric symptomatology and personality traits. Euclidean distance analysis between the personal attributes in the actual selves in the physical and virtual worlds for the similarities of the 2 selves was performed in the analysis. RESULTS: The current primary findings are the negative correlations between the similarity of the personal attributes in the physical actual self and virtual actual self, and smartphone use time, smartphone addiction as well as anxiety symptomatology respectively (P<
.05 to P<
.01). CONCLUSIONS: The current findings provide empirical evidence for the importance of maintaining a congruent self across the physical and virtual worlds, regulating smartphone use time, preventing smartphone addiction, and safeguarding mental health.