Despite the adoption of minimally invasive techniques, recovery after abdominal surgery takes a long time. Electronic health (eHealth) modalities can provide guidance to patients, facilitating early return to normal activities. We aimed to assess the impact of a personalised eHealth programme on patients' return to normal activities after major abdominal surgery. This single-blind, randomised, placebo-controlled trial was done at 11 teaching hospitals in the Netherlands. Eligible participants were aged 18-75 years who underwent a laparoscopic or open colectomy or hysterectomy. An independent researcher randomly allocated participants (in a 1:1 ratio) to either the intervention or control group by use of computer-based randomisation lists, with stratification by sex, type of surgery, and hospital. Participants in the intervention group had access to a perioperative, personalised eHealth programme consisting of both standard face-to-face care and eHealth, that comprised interactive tools offering goal attainment and a personalised outcome measurement, which managed recovery expectations and provided postoperative guidance tailored to each patient. Patients were provided with an activity tracker and had access to a website and mobile app with an electronic consultation (eConsult) functionality. The control group received standard care and access to a placebo website containing recovery advice provided by the hospital. The primary outcome was the number of days between surgery and personalised return to normal activities, assessed with Kaplan-Meier curves. Intention-to-treat and per-protocol analyses were done with a Cox regression model. This trial is registered with the Netherlands National Trial Register (NTR5686). Between Feb 11, 2016, and Aug 9, 2017, 355 participants were randomly assigned to the intervention (n=178) or control (n=177) groups. 342 participants were included in the intention-to-treat analysis. The median time until return to normal activities was 52 days (IQR 33-111) in the intervention group, and 65 days (39-152) in the control group (adjusted hazard ratio 1·30 [95% CI 1·03-1·64]; p=0·027). The frequency of postoperative complications did not differ between groups. This eHealth programme, delivering personalised care based on goal attainment scaling, enabled patients to return to their normal activities 13 days earlier than those who received standard care. ZonMw.