The rapid growth of mobile applications has transformed how businesses interact with customers, making service quality a critical factor in customer retention and loyalty. This study investigates the impact of mobile app service quality on customer loyalty, using the JAHEZ food ordering app in Saudi Arabia as a case study. The research examines key service quality dimensions, including security, reliability, usability, customization, and customer support, to determine their influence on user satisfaction and loyalty. Data was collected through an online survey of 159 participants, and the results were analyzed using factor analysis, regression, and moderation analysis. Findings imply that improved service quality directly enhances customer loyalty, with usability and security playing significant roles. While the behavior of delivery drivers showed a positive correlation with customer loyalty, it did not significantly moderate the relationship between service quality and loyalty. The insights from these findings highlight the importance of continuous improvement in app features and customer support services to maintain a competitive advantage.