BackgroundDuring the COVID-19 pandemic, online collaborative problem solving (online CPS) has become one of the most crucial learning methods to develop students' learning performance. However, it remains unclear of the effectiveness of the online CPS method on students' learning performance.ObjectivesTo explore the overall effect of online CPS methods on students' learning performance and identify the moderating factors that influence this impact, we employed a meta-analysis approach to analyse the combined effects of 31 articles.ResultsThe results showed that the online CPS method had a medium impact on students' learning performance, with an overall effect size of 0.526. The moderator analysis indicated that the online CPS method was more effective for (a) college preparatory learners, (b) the discipline of Economics, (c) grouping method of assigned, (d) teacher-led instruction, (e) study duration of 2 to 4 weeks, (f) group size of 3-5 members, (g) synchronous online environment and (h) cognitive performance.ImplicationsBased on these findings, we recommend using the online CPS to improve students' cognitive and affective learning performance. To enhance students' social learning performance, instructors should design reasonably to use collaborative scaffolding to engage students purposefully and constructively in online CPS activities. What is already knownDuring the COVID-19 pandemic, the online collaborative problem solving (CPS) method is gaining increased popularity.The impact of the online CPS method on students' learning performance has aroused the great interest of scholars.Research on the effectiveness of the online CPS method on students' learning performance is inconsistent.Research on the influence of the online CPS method on students' learning performance, such as in cognitive, affective and social three-dimensional learning performance.The online CPS method had a medium positive effect on students' cognitive performance and a moderate to low positive impact on students' affective and social performance.Considering some moderating variables (such as group size, educational level, group method, study duration, discipline, intervention measure and online environment), explore the effectiveness of the online CPS method on students' learning performance.Implications for practiceWe recommend using the online CPS method to improve students' cognitive and affective learning performance.To enhance students' social learning performance, instructors should design reasonably to use collaborative scaffolding to engage students purposefully and constructively in online CPS activities.