BACKGROUND: Smartphone addiction (SA) refers to a behavioral disorder characterized by an irresistible compulsion to excessively engage with mobile devices. Currently, the evidence regarding the relationship between physical activity (PA), exercise intensity (EI), and SA is limited, particularly within Chinese populations. This study aims to explore the correlation between PA, EI, and SA, specifically investigating how PA and EI impact SA to better understand the nature of this relationship. METHODS: A cross-sectional study was conducted involving college students from over 20 universities in Western China. Data were collected on participants' engagement in PA, EI, and SA. Additionally, covariates such as age, gender, ethnicity, academic classification, university location, discipline, year of study, hometown region, sibling status, relationship status, and social interactions were recorded. Multivariate logistic regression models were used to assess the association between PA, EI, and SA. Stratified and interaction analyses were performed to examine whether the relationship remained consistent across different subgroups. RESULTS: Of the 3,506 college students surveyed, 1,905 (54.3%) experienced SA. The prevalence of SA was 11.3% lower in the group that engaged in PA compared to those who did not. In the fully adjusted model, PA was negatively associated with SA (OR = 0.70, 95% CI: 0.59-0.82, CONCLUSION: The findings indicate a significant negative association between PA, EI, and SA, highlighting the potential of promoting PA and higher EI as strategies to reduce SA among college students.