Major abdominal surgery is associated with a high rate of post-operative complications with increased risk of adverse surgical outcomes due to the presence of frailty. This study aims to evaluate the effectiveness of the multimodal Recovery of Surgery in the Elderly (ROSE) prehabilitation program with supervised exercise in mitigating postoperative functional decline when compared to standard care. The ROSE program enrolled ambulant patients who were 65years and above, had a Clinical Frailty Scale score of 4 or more and were planned for major abdominal surgery. Participation in supervised exercise sessions before surgery were compared with standard physiotherapy advice. The primary outcome was 6-min walk test (6MWT) distance assessed at baseline, after prehabilitation and 30days follow-up after surgery. Secondary outcomes included physical performance, length of hospital stay and postoperative morbidity. Data from 74 eligible patients, 37 in each group, were included. Median age was 78years old. Forty-two patients (22 in Prehab group and 20 in control group) with complete 6MWT follow-up data at 30days follow-up were analysed for outcomes. Most patients underwent laparoscopic surgery (63.5%) and almost all of the surgeries were for abdominal malignancies (97.3%). The Prehab group had an increase in 6MWT distance at the 30-day follow up, from a baseline mean (SD) of 277.4 (125) m to 287.6 (143.5) m (p=0.415). The 6MWT distance in the control group decreased from a baseline mean (SD) of 281.7 (100.5) m to 260.1 (78.6) m at the 30-day follow up (p=0.086). After adjusting for baseline 6MWTdistance and frailty score, the Prehab group had significantly higher 6MWT distance at 30-day follow-up than control (difference in adjusted means 41.7m, 95% confidence interval 8.7-74.8m, p=0.015). There were no significant between-group differences in the secondary outcomes. A multimodal prehabilitation program with supervised exercise within a short time frame can improve preoperative functional capacity and maintain baseline functional capacity in frail older adults undergoing major abdominal surgery.