Background <p>Despite recognizing the cardiovascular disease risk in women with pre-eclampsia (PE) pregnancy and their children, there is a lack of implementation studies on web-based lifestyle interventions for this population. Implementation studies are needed to identify ways to incorporate support systems into healthcare settings for this high-risk population. The aim of the study was to assess the implementation of a 12-month web-based lifestyle intervention for families (mothers <i>n</i> = 110, fathers <i>n</i> = 66, children <i>n</i> = 107) 8–12 years after PE.</p> Methods <p>The FINNCARE study intervention comprised a baseline face-to-face session with a nutritionist, 12 months of access to a web-based interactive program (“portal”), and at least one phone contact. Families received counselling from a nutritionist. The portal featured 39 thematic pages. We assessed reach (interest, participation rate, and characteristics), compliance (measurement retention, engagement as portal logins, dietary tests completion, goal setting, physical activity application download, and interactivity), and acceptability (adherence, technical issues, and parental experience).</p> Results <p>Participation rate was 53% for mothers, 20% for fathers, and 48% for children. Retention was higher among participants with lower BMI, higher education, and those who were married or cohabiting. Engagement varied: 29% logged in to 30–39 pages (high), 27% to 20–29 pages (moderate), and 44% to 0–19 pages (low). Socioeconomic and baseline health factors were not associated with engagement. Among high and moderate engagement groups, 50% set health goals, compared to 17% in the low engagement group. Higher engagement was also correlated with completed number of dietary tests, the adoption of physical activity application, and interactivity with the nutritionist. Mothers showed greater acceptability than fathers, with the most significant differences observed in its perceived usefulness (<i>p</i> &lt; 0.001) and the implementation of lifestyle changes (<i>p</i> = 0.015).</p> Conclusion <p>This study is the first to show that a 12-month web-based lifestyle intervention can effectively reach and engage families with different education and income levels 8–12 years after PE pregnancy. Significant variability in compliance suggests a need for additional strategies to improve overall portal utilization. Future research should also focus on increasing the reach and acceptability of the intervention, particularly among fathers.</p> Trial Registration <p>number (ClinicalTrials.gov) and date: NCT04676295, 12.7.2020, retrospectively registered.</p>