Abstract Background Online resources present various possibilities for health promotion, also in the growing older adult population. Tailored online services aiming to support social participation among users could potentially promote older adults’ psychosocial health. In the @geing Online project an online application is developed, focusing on access to meaningful social activities among older adults in rural areas in Finland and Sweden. The innovation project (2017-2020) is funded by the Interreg Botnia-Atlantica programme (European Regional Development Fund). Methods A collaborative, user-centred design approach is applied when developing the online application, allowing older potential users and personnel groups from the social and health care sector to evaluate application features in a step-wise process. The inclusion of personnel groups allows for the exploration of the feasibility of introducing the tool in home care services and similar relevant contexts from an organizational perspective. Further, the inclusion of regional IT-companies presents opportunities for them to develop their competence regarding eHealth tools and older adults as a target group. Results An advanced prototype of the application and its core features is presented. Promising approaches and outcomes regarding the co-creation methods applied to ensure the involvement of stakeholders in the development process are elaborated upon. Challenging issues related to the project theme, such as stereotypical and negative views of older adults’ competences and motivation related to application use are also discussed. Conclusions The project highlights possibilities - but also challenges - when co-creating a social application together with older adults, some of whom have no experience in internet use. The gathered project outcomes will provide lessons on the potential of new technologies for delivering health promotion initiatives among older adults. Key messages Tailored online services aiming to support social participation among users provide possibilities for promoting psychosocial health in the growing population of older adults. Application development utilizing a user-centered design approach can be implemented even if the end-users are not familiar with the internet or application use.