International data suggest that exposure to nature is beneficial for mental health and well-being . The restrictions related to the COVID-19 pandemic have created a setting that allows us to investigate the importance of greenness exposure on mental health during a period of increased isolation and worry . Based on 2060 responses from an online survey in Stockholm County, Sweden, we investigated: (1) whether the COVID-19 pandemic changed peoples ’ lifestyle and nature-related habits, and (2) if peoples ’ mental health differed depending on their exposure to greenness . Neighborhood greenness levels were quantified by using the average normalized difference vegetation index (NDVI) within 50 m , 100 m , 300 m, and 500 m buffers surrounding the participant ’ s place of residence . We found that the number of individuals that reported that they visited natural areas “ often ” was significantly higher during the pandemic than before the pandemic . Higher levels of greenness surrounding one ’ s location of residence were in general associated with higher mental health/well-being and vitality scores, and less symptoms of depression, anxiety, and perceived and cognitive stress, after adjustments for demographic variables and walkability . In conclusion, the results from the present study provided support to the suggestion that contact with nature may be important for mental health in extreme circumstances.