Informal green spaces (IGSs) play an essential role in enhancing urban well-being by offering restorative environments, yet the impact of visitor behaviors on perceived restorativeness (PR) remains underexplored. This study investigates how different spatio-temporal behaviors influence PR in IGS, providing urban planners with actionable insights to optimize these spaces for better user experiences. Using a visitor-employed photography (VEP) survey and post-visit PR assessments, K-means clustering was applied to identify distinct visitor behavior patterns. Correlation analysis further explored the relationships between these patterns and PR; the results reveal three unique clusters of visitor behaviors—fast, extensive exploration; moderate, focused exploration; and slow, thorough exploration—each showing distinct impacts on PR. Visitors who engage in rapid, broad exploration perceive larger, navigable spaces as more restorative, while those focusing on specific or in-depth exploration emphasize psychological aspects like escape and fascination. These behavioral patterns demonstrate varying strengths in their association with restorative experiences; This study underscores the importance of integrating spatio-temporal behavior data with PR assessments, highlighting how the physical and psychological features of IGS influence visitor experiences. These findings offer critical insights for designing and managing IGS to accommodate diverse user needs and promote urban well-being.