Online collaborative learning is increasingly used in online courses in higher education, but assessing student online collaborative learning presents unique challenges as well as interesting opportunities. Thus, it is critical to gain a clear picture of online group collaboration assessment strategies, including group learning assessment methods and examining the effectiveness, challenges, and opportunities in online education. The present study systematically reviewed 12 empirical studies on online collaborative learning assessment in higher education published in journals from 2011 to 2021. The results show that diverse strategies were used to facilitate group collaboration, including group agreements, project planning, role assignments, problem-based projects, and instructor feedback. The reviewed studies primarily evaluated learners through instructor evaluation, peer evaluation, and self-evaluation methods. The most common strategy was instructor assessment, while self-evaluations were used the least. The findings of this mapping review provide practical examples for future online group collaborative learning assessment research and practice.