The objective of the current study was to investigate, for the first time, the association between individual-level residential greenspace and redemption of antidepressant drugs in a longitudinal nationwide population-based sample in Sweden. A nationwide population-based sample of adults residing in Sweden was studied during 2013–2016 (Nindividuals = 108716; Nobservations = 324378). Residential greenspace land cover was assessed via high resolution geographic information systems, at 50, 100, 300, and 500 m buffers around individual residences. Antidepressant redemptions were assessed through the Swedish National Prescribed Drug Register. Greenspace-antidepressant associations were analyzed using generalized estimating equations (GEE), adjusting for demographic, socioeconomic and urban factors. Higher greenspace within 50–500 m residential buffer zones was associated with lower levels of prevalent antidepressant redemptions (50 m, odds ratio [OR] 0.878; 100 m, OR 0.891; 300 m, OR 0.873; 500 m, OR 0.899), while only greenspace in the 50 m buffer was associated with incident antidepressant redemptions (OR 0.853), in covariate-adjusted models. In conclusion, residential greenspace is associated with statistically significantly lower prevalent and incident antidepressant medication redemptions. The association is particularly salient for greenspace in the closest buffer zone around the residence. The results underscore the importance of green infrastructure and greenspace in the immediate residential-surrounding environment for mental health, and further point towards the need for an environmental psychiatry framework, and the importance of integrating health and environmental policies, urban planning and greening.