An increasing number of older adults are undergoing major surgery. Frailty, multimorbidity and sarcopenia, over and above chronological age, are major determinants of postoperative complications, loss of independence and mortality. Comprehensive geriatric assessment (CGA) and multimodal prehabilitation can mitigate this risk, but hospital-based pathways are constrained by workforce, transport and geography, and these barriers often exclude the frailest patients. This narrative review examines how digital technologies can support preoperative assessment, optimisation, and prehabilitation in older surgical patients. We outline the biological rationale for repeated, dynamic assessment of resilience; review electronic frailty indices, digital CGA, remote functional testing and wearable-derived measures; and appraise remotely delivered exercise, nutritional, psychological, cognitive and medical optimisation. Digital tools appear feasible and can stratify risk in older adults; however, there is not yet evidence that they improve clinical outcomes on their own, and the largest trial of home-based prehabilitation in frail older adults found no benefit, with low adherence. We describe two real-world models from the UK: a remotely delivered multidisciplinary service at University College London Hospitals (UCLH) and PreActiv, a rule-based, individualised digital platform. In 274 patients treated at UCLH, sit-to-stand performance and health-related quality of life improved after prehabilitation and remained above baseline after surgery. Finally, we discuss sensor validity, digital inclusion, governance, health economics and the potential role of artificial intelligence.