School effectiveness refers to an educational institution's ability to achieve its predetermined goals, especially regarding student learning outcomes, development, and well-being. Although forming and strengthening partnerships between schools is commonly used to improve school effectiveness, empirical evidence on the connection between school collaboration and school effectiveness remains insufficient. This study investigates the relationship between school collaboration and effectiveness by employing a hierarchical linear model based on a value-added analysis of student scores in selected schools in a central Chinese city. We found that some student- and school-level variables significantly influenced students' achievement. After controlling for both student and school demographic variables, the study results indicated that collaborative schools exhibited greater school effectiveness than non-collaborative schools, and the effectiveness continued improving as collaborative schools continued to grow. In general, it is viable to employ the value-added approach to assess the impact of school collaboration within the Chinese education system.