Research has shown that families' participation in a cardiovascular disease (CVD) prevention programme could boost early adoption of healthy lifestyle behaviours in families. Behaviour-based, eHealth interventions are a potential means of achieving this. This study aimed to explore expectations of families-parents and children-at risk of CVD towards the design and functionality of an eHealth family-based CVD-risk reduction programme 'Health-e-Hearts'. Three online focus groups were conducted with six families comprising at least one parent at risk of CVD and at least one child aged 5-17 years. The focus groups were video and audio recorded and transcribed. Content analysis was used to synthesize and identify key categories and subcategories regarding development of and engagement with an eHealth programme. Three categories emerged: experiences of health apps and devices; eHealth application needs of family members; and motivators for using an eHealth programme. Experiences included using health apps individually and inconsistently. Needs included personalization, free and easy-to-use, time efficient, and multiple content formats. Motivators for engaging with the programme included goal setting, rewards, and competition. Families' expectations of an eHealth family-based CVD-risk reduction programme include the incorporation of personalized, easy-to-use design features and motivators for engaging with the programme. Family involvement in the development of an eHealth programme such as 'Health-e-Hearts' has the potential to boost early adoption of healthy lifestyle behaviours among all family members. [Abstract copyright: © The Author(s) 2022. Published by Oxford University Press on behalf of the European Society of Cardiology.]