Digital twins are moving from descriptive building models toward continuously synchronised cyber-physical systems capable of testing, diagnosing, predicting and documenting safety performance. This review examines how that transition can support fire safety testing, commissioning and risk management in Saudi smart buildings. This review adopted a structured integrative approach to synthesise peer-reviewed research on digital twins, building information modelling, Internet of Things sensing, artificial intelligence, fire dynamics, evacuation, predictive maintenance, commissioning, and Saudi digital-construction readiness. The evidence indicates that the strongest near-term value lies not in a single ‘fire twin’ application but in a lifecycle assurance architecture that connects design intent, test evidence, live sensor states, functional cause-and-effect logic, maintenance history and emergency response models. Existing studies demonstrate credible capabilities in fire-scene reconstruction, intelligent fire-protection control, evacuation tracking, dynamic route guidance and predictive maintenance. Still, they remain fragmented across prototypes, individual systems and non-Saudi test environments. For Saudi Arabia, adoption therefore depends on interoperable data models, auditable commissioning rules, calibrated sensors under harsh environmental conditions, cybersecurity, workforce competence and governance that preserves an authoritative record from design through operation. The review proposes a fire-safety digital-twin assurance model and identifies research priorities for performance-based validation, continuous commissioning, uncertainty-aware risk analytics and regulatory acceptance. The resulting agenda positions the digital twin as an evidence infrastructure for safer, more transparent, and more resilient smart-building operation, rather than merely a visualisation platform.