Background: Happiness is a multidimensional concept linked to well-being and mental health, mainly in students in demanding academic programs. With the increasing use of digital devices, screen time appear as a potential factor influencing happiness. This study aimed to assess the level of happiness in undergraduate nursing students in Saudi Arabia and examine its relationship with screen time, gender, and academic level. Methods: A cross-sectional study was conducted in 100 nursing students using the Oxford Happiness Questionnaire (OHQ) and a structured survey on screen time habits. Data were analyzed using Pearson correlation, t-test, ANOVA, and linear regression. Results: The mean happiness score was 3.93 (SD = 0.82), which indicate a moderate level of happiness. There was a significant negative correlation between happiness scores and screen time on both mobile devices (r = –0.298, p = 0.003) and television (r = –0.239, p = 0.016). No significant differences in happiness were observed based on gender or academic level. The regression model explained 13.5% of the variance in happiness scores. Conclusion: Excessive screen time is inversely associated with happiness levels in nursing students. Institutions should consider integrating mental wellness strategies and digital literacy programs into nursing education to improve psychological well-being.