To test the mediatory role of kinesiophobia between greenspace and physical activity, we conducted a cross-sectional survey and recruited 801 participants with chronic low back pain. The level of greenspace was assessed using both perceived greenspace and the Normalized Difference Vegetation Index (NDVI). The frequency of walking and moderate and vigorous physical activities was measured using a brief assessment, while kinesiophobia was evaluated using the 11-item Tampa Scale for Kinesiophobia (TSK-11). The results revealed that perceived greenspace was positively associated with all measured physical activities, and was negatively associated with kinesiophobia. Meanwhile, NDVI was only positively associated with moderate and vigorous physical activity. Kinesiophobia played a marginal but significant mediating role in the association of perceived greenspace with walking, moderate physical activity, and vigorous physical activity. In conclusion, our findings offer early evidence of associations and pathways between greenspace and physical activity among individuals with chronic low back pain.