Objectives To evaluate the cost-effectiveness and cost-utility of an internet-based perioperative care programme compared with usual care for gynaecological patients. Design Economic evaluation from a societal perspective alongside a stepped-wedge cluster-randomised controlled trial with 12 months of follow-up. Setting Secondary care, nine hospitals in the Netherlands, 2011-2014. Participants 433 employed women aged 18-65 years scheduled for a hysterectomy and/or laparoscopic adnexal surgery. Intervention The intervention comprised an internet-based care programme aimed at improving convalescence and preventing delayed return to work (RTW) following gynaecological surgery and was sequentially rolled out. Depending on the implementation phase of their hospital, patients were allocated to usual care (n=206) or to the intervention (n=227). Main outcome measures The primary outcome was duration until full sustainable RTW. Secondary outcomes were quality-adjusted life years (QALYs), health-related quality of life and recovery. Results At 12 months, there were no statistically significant differences in total societal costs (€-647; 95% CI €-2116 to €753) and duration until RTW (-4.1; 95% CI -10.8 to 2.6) between groups. The incremental cost-effectiveness ratio (ICER) for RTW was 56; each day earlier RTW in the intervention group was associated with cost savings of €56 compared with usual care. The probability of the intervention being cost-effective was 0.79 at a willingness-to-pay (WTP) of €0 per day earlier RTW, which increased to 0.97 at a WTP of €76 per day earlier RTW. The difference in QALYs gained over 12 months between the groups was clinically irrelevant resulting in a low probability of cost-effectiveness for QALYs. Conclusions Considering that on average the costs of a day of sickness absence are €230, the care programme is considered cost-effective in comparison with usual care for duration until sustainable RTW after gynaecological surgery for benign disease. Future research should indicate whether widespread implementation of this care programme has the potential to reduce societal costs associated with gynaecological surgery. Trial registration number NTR2933; Results.