Background Nomophobia and social anxiety have significant negative implications for the physical and mental health of students, as well as their academic performance. Considering the variability in findings across studies on the prevalence of nomophobia and social anxiety, this study aimed to investigate the prevalence of nomophobia, its associated factors, and its relationship with social interaction anxiety among nursing students. Methods This cross-sectional descriptive-analytical study was conducted between August 22nd and September 23rd, 2023, at the School of Nursing and Midwifery in Kermanshah, located in western Iran. A convenience sampling method was employed, resulting in the recruitment of 258 participants. Data were collected using a three-part questionnaire, including a demographic information form, the Nomophobia Questionnaire (NMP-Q) to assess the severity of nomophobia, and the Social Interaction Anxiety Scale (SIAS) to measure social anxiety levels. Data were analyzed using STATA, version 14. Descriptive statistics were used to summarize demographic and clinical characteristics. The Chi-square test, one-way analysis of variance, the Pearson correlation coefficient, and linear regression modeling were employed for inferential analysis. Results All participating nursing students (n = 258) exhibited some degree of nomophobia. The prevalence of mild, moderate, and severe nomophobia was 40.7%, 40.3%, and 19%, respectively. Furthermore, 25.6% of the students experienced social anxiety. A significant positive correlation was found between nomophobia scores and social interaction anxiety (r =.37, P <.001). Social interaction anxiety emerged as the only significant independent predictor of nomophobia (P <.001), explaining 21% of the variance in nomophobia scores. Conclusions The results indicate both the prevalence of nomophobia and social anxiety, as well as the correlation between these two factors among students. Considering the numerous risks associated with nomophobia and social interaction anxiety, it is essential to optimize technology use and improve social interactions among students. Identifying students at risk of nomophobia and social interaction anxiety and providing psychological counseling services to them should be prioritized.