Background A significant number of university students experience loneliness and mental health issues on daily basis. While methods to promote social and mental health are urgently needed both nationally and internationally, there is a lack of evidence-based interventions with such focus. To meet these needs, `Unite Students´ was designed, initially framed as a universal, group-based, health-promotive intervention focusing on increased health-literacy, mental resilience, social connectedness, meaning and mattering, and agency through collective and societal understanding of social and mental health. To further the development of a relevant and attractive health-promotive method among university students, the `Unite Students´ was early on advanced in overlapping co-creative processes, involving different stakeholders in separate studies. This study pioneers the co-creative development of `Unite Students´ involving student perspectives and ideas. The aim was to co-create a useful social and mental health-promotive intervention, addressing students´ contemporary challenges and needs, as well as their proposed themes, pedagogical approaches, and elements for meaningful change.Methods The participating students in this study were recruited by open announcements at a large Swedish university in three rounds between 2021–2024, involving new groups of students each year, with a sequence of three workshop-sessions for each group. A total of 19 students from 13 different university programs were involved. The initial participatory workshops were based on co-creative methods, such as brainstorming and design-thinking, while the ending workshops included reflections, modifications, and refinement of the intervention.Results Students viewed loneliness and mental health challenges as silenced, systemic and interconnected. Workshops proposed scalable, discussion-based support emphasizing relational skills, social connectedness, and university spaces for deeper conversations, highlighting pedagogics of peer-professional co-learning, and the need for both micro-level health promotion and broader structural change to improve student- and living conditions and distress.Conclusions Students emphasized the value of contributing to the development of an intervention promoting social and mental health and believed it could have major impact on sense of connectedness and value at university; room for health-related dialogues; improved wellbeing; completion of education; life-prospects, and future working life. These reverberations hold potential in both individual, societal, public health, and socio-economic perspectives.