People living with frailty account for a significant proportion of hospital inpatients and are at increased risk of adverse events during admission. The understanding of frailty remains variable among hospital staff, and there is a need for effective frailty training across multidisciplinary teams. Simulation is known to be advantageous for improving human factor skills in multidisciplinary teams. In situ simulation can increase accessibility and promote ward team learning, but its effectiveness with respect to frailty has not been explored. A single-centre, multi-fidelity, inter-professional in situ frailty simulation programme was developed. One-hour sessions were delivered weekly using frailty-based clinical scenarios. Mixed-method evaluation was used, with data collected pre- and post-session for comparison. In total, 86 multidisciplinary participants attended 19 sessions. There were significant improvements in self-efficacy rating across 10 of 12 human factor domains and in all frailty domains (p < 0.05). The common learning themes were situational awareness, communication and teamwork. Participants commented on the value of learning within ward teams and having the opportunity to debrief. In situ simulation can improve the self-efficacy of clinical and human factor skills related to frailty. The results are limited by the nature of self-reporting methods, and further studies assessing behavioural change and clinical outcomes are warranted.