Citizen science – the active participation of lay people in research – may yield crucial local knowledge and increase research capacity. Recently, there is growing interest to understand benefits for citizen scientists themselves. We studied the perceived impacts of participation in a public health citizen science project on citizen scientists in a disadvantaged neighbourhood in the Netherlands. Local citizen scientists, characterised by low income and low educational level – many of whom were of migrant origin – were trained to interview fellow residents about health-enhancing and health-damaging neighbourhood features. Experiences of these citizen scientists were collected through focus groups and interviews and analysed using a theoretical model of potential citizen science benefits. The results show that the citizen scientists perceived participation in the project as a positive experience. They acquired a broader understanding of health and its determinants and knowledge about healthy lifestyles, and took action to change their own health behaviour. They reported improved self confidence and social skills, and expanded their network across cultural boundaries. Health was perceived as a topic that helped people with different backgrounds to relate to one another. The project also induced joint action to improve the neighbourhood’s health. We conclude that citizen science benefits participants with low educational or literacy level. Moreover, it seems to be a promising approach that can help promote health in underprivileged communities by strengthening personal skills and social capital. However, embedding projects in broader health promotion strategies and long-term engagement of citizen scientists should be pursued to accomplish this.