OptiBooking is a predictive decision-support system developed to address the challenges of hotel booking cancellations and ineffective overbooking strategies within the Sri Lankan hospitality industry. The solution is specifically designed for small to medium-sized hotels, which form the majority of Sri Lanka’s hotels and are most vulnerable to fluctuations in guest reservations. The system provides a web interface that allows front desk staff, managers, and super users to perform key tasks such as adding new bookings manually or uploading bulk bookings via CSV files, viewing and managing reservations, monitoring cancellation likelihoods, and implementing overbooking strategies. Different user roles are defined to provide access privileges to maintain security and usability across staff levels. The backend of the system is built using Python, where core booking operations, cancellation probability predictions, and automated customer email notification features are handled. A trained machine learning model predicts the likelihood of cancellation based on booking characteristics, supporting proactive operational decision-making. Persistent booking data, room data, and prediction results are stored in a MySQL database. The OptiBooking project not only improves operational efficiency by reducing last-minute cancellations and increasing occupancy rates but also promotes sustainable digital transformation in the hospitality sector. Designed with modularity, accessibility, and future scalability in mind, OptiBooking lays a strong foundation for real-world adoption and continued enhancement.