INTRODUCTION: Nomophobia, the fear of being without a mobile phone, is increasingly prevalent among university students, impacting their psychological well-being and academic performance. This study assesses the level of knowledge and the psychological, academic, and social outcomes associated with nomophobia among students at King Saud University, Riyadh, Saudi Arabia. METHODS: A descriptive cross-sectional design was employed, involving 350 undergraduate students recruited via convenience sampling. Data were collected using a structured questionnaire adapted from the Nomophobia Questionnaire (NMP-Q). Statistical analyses, including descriptive statistics, Pearson correlation, and multiple regression, were conducted using IBM SPSS. RESULTS: The majority of participants (51.4%) exhibited moderate knowledge of nomophobia. Higher nomophobia scores were significantly associated with lower academic performance (r = -0.35, p < 0.001) and greater psychological distress, including anxiety (mean score = 5.2) and panic when phone battery was low (mean score = 4.8). Regression analysis identified gender (β = 0.28, p = 0.001) and smartphone ownership (β = 0.20, p = 0.003) as predictors of nomophobia. DISCUSSION: The findings highlight nomophobia's negative impact on students' academic and psychological well-being, emphasizing the need for educational interventions to promote healthier smartphone usage. Addressing nomophobia through targeted strategies could improve academic outcomes and overall student wellness.