Few studies have highlighted perceptions of urban natural open space systems: land specifically excluded from development to protect ecosystem services. We used a local metropolitan city in South Africa to explore community perceptions of its natural open space system through individual qualitative interviews (n = 40). The objectives were: (1) to identify ecosystem services and disservices associated with the city’s natural open space system, and the reasons thereof, by exploring the relational values of nature held by a diverse socioeconomic spectrum of urban residents; and (2) to identify priorities for protecting the natural open space system by enhancing the benefits and minimizing ecosystem disservices. Reference to ecosystem services and disservices were coded according to the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) categorization of nature’s contribution to people. Non-material services (relational benefits) were impacted by exploitative material uses, access concerns and (mis)management. Challenges and opportunities identified relate to nature as a resource for supporting livelihoods and lifestyles; community outreach and employment opportunities; personal safety, health and aesthetic concerns; and lack of political accountability and municipal planning in terms of the management of natural open spaces. Innovative collaborative management and stewardship interventions with ecological and socioeconomic benefits should be prioritized to protect the natural open space system.