Abstract Background As smartphones become more accessible and more psychologically gratifying, problematic smartphone use has emerged with negative mental health consequences, especially in young adults with poor social skills and self -confidence issues. The current study aims to assess the rate of occurrence of smartphone addiction and to highlight the relationship between smartphone addiction and social phobia and its severity in a sample of female university students. Subjects and Methods This is a cross-sectional study including 540 female students in the first medical school year divided equally among practical and theoretical faculties after excluding students with psychiatric disorders except for those with social phobia using the SCID-I scale. Subjects were assessed with the Social Phobia Inventory and the Smartphone Addiction Scale for severity of both social phobia and smartphone addiction respectively. Results Out of 540 female students, 28.7% have severe smartphone addiction with higher number in students of academic faculties, also, 71.86% of the whole sample have social phobia with 22.78%, 21.85%, 16.3%, and 10.93% reporting mild, moderate, severe, and very severe social phobia scores respectively. The number of students having very severe social phobia scores in the academic group is higher than that in the practical group. Also the study shows a statistically significant relation between smartphone addiction and social phobia. Conclusion There is a high rate of distribution of social phobia in young adult females, which is accompanied with a high rate of occurrence of smartphone addiction, so, there is a need for raising the public awareness regarding hazards of problematic smartphone use especially in students and the for highlighting the importance of screening of different psychiatric disorders, as social phobia in such population.