Background: Instructing and guiding patients after surgery is essential for successful recovery. However, the time that health-care professionals can spend with their patients postoperatively has been reduced because of efficiency-driven, shortened hospital stays. We evaluated the effect of a personalised e-health-care programme on return to normal activities after surgery. Methods: A multicentre, single-blind, randomised controlled trial was done at seven teaching hospitals in the Netherlands. Patients aged 18–75 years who were scheduled for laparoscopic cholecystectomy, inguinal hernia surgery, or laparoscopic adnexal surgery for a benign indication were recruited. An independent researcher randomly allocated participants to either the intervention or control group using computer-based randomisation lists, with stratification by sex, type of surgery, and hospital. Participants in the intervention group had access to a perioperative, personalised, e-health-care programme, which managed recovery expectations and provided postoperative guidance tailored to the patient. The control group received usual care and access to a placebo website containing standard general recovery advice. Participants were unaware of the study hypothesis and were asked to complete questionnaires at five timepoints during the 6-month period after surgery. The primary outcome was time between surgery and return to normal activities, measured using personalised patient-reported outcome measures. Intention-to-treat and per-protocol analyses were done. This trial is registered in the Netherlands National Trial Register, number NTR4699. Findings: Between Aug 24, 2015, and Aug 12, 2016, 344 participants were enrolled and randomly allocated to either the intervention (n=173) or control (n=171) group. 14 participants (4%) were lost to follow-up, with 330 participants included in the primary outcome analysis. Median time until return to normal activities was 21 days (95% CI 17–25) in the intervention group and 26 days (20–32) in the control group (hazard ratio 1·38, 95% CI 1·09–1·73; p=0·007). Complications did not differ between groups. Interpretation: A personalised e-health intervention after abdominal surgery speeds up the return to normal activities compared with usual care. Implementation of this e-health programme is recommended in patients undergoing intermediate-grade abdominal, gynaecological, or general surgical procedures. Funding: ZonMw.