Citizen Observatories (COs) are innovative mechanisms to engage citizens in monitoring and addressing environmental and societal challenges. However, their effectiveness hinges on seamless data crowdsourcing, high-quality data analysis, and impactful data-driven decision-making. This paper validates how the GREENGAGE project enables and encourages the accomplishment of the Citizen Science Loop within COs, showcasing how its digital infrastructure and knowledge assets facilitate the co-production of thematic co-explorations. By systematically structuring the Citizen Science Loop—from problem identification to impact assessment—we demonstrate how GREENGAGE enhances data collection, analysis, and evidence exposition. For that, this paper illustrates how the GREENGAGE approach and associated technologies have been successfully applied at a university campus to conduct an air quality and public space suitability thematic co-exploration.