Progress towards the United Nations’ Sustainable Development Goals (SDGs) is monitored using a set of targets and indicators. Gaps in official datasets have led to calls for the inclusion of data generated through citizen science (CS) and allied approaches. Co-benefits of CS mean these approaches could also contribute to localising, defining, and achieving the SDGs. However, mapping of current and potential contributions is needed, as well as an understanding of the challenges these approaches present. We undertake a semi-systematic review of past and current CS projects and assess them against dimensions of CS—spatial, temporal, thematic, process, and management—and their value for the SDGs set out by Fritz et al. in 2019, focusing on low and middle income country (LMIC) cities as key environments in the battle for sustainability. We conduct interviews with project leaders to further understand the challenges for CS in these contexts. We find opportunities for projects to monitor and achieve a wide range of goals, targets, and indicators. However, we find fewer projects in low income countries when compared with middle income countries. Challenges include balancing local needs with national monitoring requirements and a lack of long-term funding. Support is needed for LMICs to achieve the potential of CS.