Problematic smartphone use (PSU), which involves an excessive and uncontrolled use of smartphones, thereby causing daily-life disturbance, has been associated with a range of negative outcomes including anxiety, depression, and deficits in social relationships. However, the relationship between PSU and maximization, which could be an explanatory factor, has not yet been thoroughly studied. Drawing on the Interaction-Person-Affect-Cognition-Execution (I-PACE) model, the current study aimed to investigate the association between PSU and maximization with the assumption that fear of missing out (FoMO) and self-esteem could mediate this relationship. Empirical data were gathered from 277 Italian university students who completed an online survey. Correlation analysis and structural equation modelling (SEM) were used to investigate the relationships among the variables. The results showed that PSU, maximization, and FoMO were positively correlated; whereas maximization and self-esteem were negatively correlated. Furthermore, FoMO and self-esteem partially mediated that relationship, suggesting that participant maximizers experience more FoMO, especially when the participants have fear of missing out on potentially “better” alternatives to social experiences and exhibit low self-esteem. Thus, higher FoMO and low self-esteem can be a driver of PSU. Finally, this study provides new insights about how maximization may have an impact on the development of addictive behaviour such as PSU.