The rise of citizen science has drawn policymakers' attention. With a shift towards participatory and transparent governance, linking policies to citizen science could contribute to create the evidence base and social acceptance for policy-making, and further counter-play populism and post-truth politics. This study aims to gain empirical understanding on how citizen-generated data from citizen science initiatives could contribute to political decision-making and problem-solving in different contexts; more specifically, we aim to explore how citizen science initiatives were formed, what opportunities and challenges are for citizen-generated data, how such initiatives lead to a citizen-driven solution in the problem-solving process, and how the contextual settings and actors’ perceptions and actions interplay and potentially play a part along the process. In this study, a conceptual model was set up through a systematic literature review. Two case studies — the case of Hollandse Luchten in the Netherlands and the case of AirBox in Taiwan — were carried out and analyzed as guided by the conceptual model. Based on the findings and insights gained from the case studies, a revised, empirically-enhanced model of citizen science for policies was developed, whereby policy recommendations were formulated.