Small waterbodies such as ponds are widely represented in cities, contributing to the blue-green infrastructure, improving human well-being. Their multifunctionality remains nevertheless infrequent, as often only a single ecosystem service is targeted when creating a pond: flood risk prevention, water purification, aesthetic value or leisure (boating, fishing). Therefore, a pond implementation in a city cannot presently be considered as a Nature-based solution, also because the promotion of native biodiversity is rarely a priority. An innovative approach would be to increase their multifunctionality, considering also the biodiversity. We investigated this hypothesis in 42 urban ponds (Geneva, Switzerland), through the assessment of biodiversity and several ecosystem services (reduction of flood risk, cooling function, water purification, carbon sequestration), and a survey among the local population. The results evidenced a lack of multifunctionality of these ponds. They performed relatively well for one ecosystem services, but markedly less for the others. For small ponds, their performance is best when considered collectively, as pondscapes, with a cumulative impact for each service. As the promotion of biodiversity was not a target of the studied ponds, consequently the richness of the native biodiversity was low. Our study evidenced that the ponds could easily be optimised to enhance their performance for several ecosystem services. Biodiversity can be enhanced by simple management measures, including a better design. The survey of the citizens underlined a very good acceptance of ponds in the city, with a recognized contribution to well-being. In conclusion, due to their small size, ponds can easily be constructed at low cost in cities, and can be optimized for multiple ecosystem services, including biodiversity, to improve human well-being. They thus represent Nature-based solutions, potentially effective to address urban societal challenges.