In an increasingly urbanized world, urban green spaces (UGS) are critical for ensuring residents’ health and well-being, due to the ecosystem services provided. Urban planning is being instigated to maximize the potential of UGS to increase responsiveness to major societal and environmental challenges and emerging policy demands. While city-wide perspectives can guide the cities’ governance approach, a more local approach is required to optimize local planning and management of UGS. In this paper we aim to identify the spatial patterns of UGS uses in Lisbon city, Portugal. Specifically, we ask if urban residents have equal accessibility to UGS within their residential zip area and what are the key factors related to residents’ decisions to visit UGS within or outside their zip. We used a Public Participation GIS to collect spatially explicit data about residents most frequented UGS. The survey was directed to respondents from different socio-demographic classes and areas of residence, by using different on-line communication channels, and conducted between February and April 2017. We collected data from 569 respondents, which corresponded to 2010 UGS locations. Our results show that resident’s do not have equitable accessibility to UGS, caused by the uneven distribution of green spaces within the city. We also found that the number of residents traveling for UGS outside their zip area (outflux) was significantly related to the green space coverage and vegetation heterogeneity in their own zip area. We found no significant relation between resident’s outflux and their sociodemographic characteristics. Our regression model determines that to have less than 50% of outflux Mediterranean cities need to have at least 25% of green space in a zip area. These results can support planners and decision-makers by providing guidance on how to identify areas of unequal accessibility and where to allocate efforts.