BackgroundThe Community Wise (CW) intervention applies a community-based approach to improve the physical fitness, self-management ability, loneliness, social cohesion, and well-being of older adults living in neighbourhoods characterized by lower socioeconomic status (SES).MethodsParticipants (N= 108) were recruited using several strategies, including door-to-door visits and community key peers. The study was based on a pre-test/post-test design. Outcomes were assessed through mixed methods using questionnaires, performance tests, semi-structured interviews, and focus-group sessions.ResultsResults showed significant improvements on aerobic endurance and shoulder flexibility, but no significant improvements on self-management ability, social cohesion, loneliness, or well-being. Qualitative data analysis did indicate that participants experienced improvements on social connectedness with members of the group, as well as on self-management ability.ConclusionThe results of the intervention seem to depend on programme fidelity and method of assessment. Adapting the intervention and including more older adults with poor health status could lead to better outcomes in the future. This results of this study should be interpreted in light of the complexity and methodological challenges of conducting a community-based health-promotion intervention for this target group.Trail registrationRetrospective registration.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12889-023-16148-y.