The smartphone is a double-edged sword for university students; it is a necessary tool for communication which also brings along negative consequences if used excessively. This cross-sectional study was conducted to identify the prevalence rate of smartphone addiction among the undergraduates, to determine psychological distress as a significant predictor of smartphone addiction, and to examine perceived social support as a significant mediator in psychological distress and smartphone addiction. A total of 112 (61 females, 51 males) undergraduates in Kuala Lumpur, Malaysia, aged 18 to 24 years were selected through the purposive sampling method. Participants completed a set of questionnaires via Google Form consisting of Kessler Psychological Distress Scale, Smartphone Addiction Scale-Short Version, and Multidimensional Scale of Perceived Social Support. SmartPLS (Partial Least Squares) which is based on the principles of path modeling and bootstrapping was employed to build the causal model. Results revealed that 66.10% of undergraduates were addicted to smartphones. Also, psychological distress significantly predicted smartphone addiction, with t-value = 7.423, p < 0.001. However, perceived social support did not mediate the relationship between psychological distress and smartphone addiction, with t-value = -0.939, p > 0.05. These findings imply that smartphones have become indispensable for undergraduates and the psychological distress of undergraduates should be given priority in reducing smartphone addiction. Suggestions are made for higher learning institutions to design intervention plans to reduce the psychological distress and smartphone addiction amongst university students.