Distracted driving is an important risk factor for traffic accidents. In particular, smartphone use while driving has become the leading cause of distraction in recent years, with the advent of smartphones and their extended functions. One noteworthy change is the addictiveness and dependency on smartphones. This study was conducted to investigate the effect of smartphone dependency on the use of smartphones while driving. A survey of 948 Korean drivers assessed smartphone dependency as well as driver experiences of calling and manipulating the smartphone while driving. Based on the survey, the relationship between smartphone dependency and the use of smartphones was examined using factor analysis and binary logistic regression. Results reveal that drivers who had high smartphone dependency were more likely to use their smartphones while driving, and the effect of smartphone dependency on manipulation was more influential than it was on calls. The results provide compelling evidence that patterns of dependent smartphone usage affect the use of smartphones while driving, especially regarding manipulation. These findings explore smartphone usage whilst driving and can provide a stepping stone toward the formulation of future policies for traffic safety.