This research explores the influence of service quality and convenience in online promotions on the sustainability of Steak Restaurants by analyzing the relationship between variables. This research aims to understand how service improvements and effective online marketing strategies contribute to customer retention and business continuity in the long term. Quantitative and qualitative research methods show that superior service quality and easy-to-use online promotions have a significant effect on customer satisfaction and loyalty. The structural model evaluation shows that service quality (SQ) and online promotion (OP) significantly influence customer satisfaction (CS), but customer satisfaction does not mediate the relationship between SQ or OP and restaurant sustainability (SUS). These findings indicate that sustainability is more influenced by external factors such as environmental awareness or regulatory incentives rather than mere customer satisfaction. The managerial implication is that restaurants need to explicitly communicate their sustainability strategies through digital promotions and transparent operational practices to enhance customer awareness and engagement with sustainability initiatives.