Leisure is an important way for residents to achieve well-being. As urbanization continues to accelerate and residents’ spiritual and cultural needs gradually increase, urban park leisure is becoming increasingly prominent in daily recreation, and recreational activities that meet residents’ short-term and frequent needs for leisure are becoming preferred. In this article, based on structural equation models, four representative urban parks in Beijing were selected as study areas to explore the relationships among three variables: leisure involvement, flow experience, and place attachment. The results showed that (1) leisure involvement had a significant positive effect on flow experience, (2) flow experience had a significant positive effect on place attachment, and (3) leisure involvement had both a significant direct effect on place attachment and an indirect effect mediated by flow experience. In addition, according to the empirical analysis of the influence of leisure behavior characteristics on leisure benefits, it was found that 1–3 h of leisure time in the park had the best leisure benefits. Therefore, a higher level of leisure involvement and a stronger flow experience can help to enhance residents’ place attachment; foster self-expression, identity, and self-actualization; and boost the benefits of leisure, which will eventually improve personal well-being and quality of life, construct and strengthen a sense of urban community, and fulfill people’s aspirations for a better life.