Self-regulated learning (SRL) has been viewed as a critical skill for learner success in MOOCs, but due to methodological limitations of self-reported measures, the relationship between SRL and learner performance remains unquantified. Therefore, this study sought to investigate how SRL impacted learner performance in MOOCs by linking clickstream data about SRL to learner performance variables. Following a social cognitive perspective of SRL, learner traces were categorized into three phases including forethought, performance/volition control, and self-reflection phase. Then separate multiple linear regression analyses were performed to examine the relationship between SRL traces in each phase and learner performance variables (e.g., quizzes scores and forum participation record). The findings of this study indicated that SRL traces in performance/volition control and self-reflection phases positively predict learners' quizzes scores. In addition, SRL traces in each of the three phases were significantly correlated to learners' forum participation, despite a small effect of the model. Particularly, self-reflective traces negatively predicted learners' forum participation but SRL traces in the other two phases had a positive relationship with the outcome variable. Practical implications about supporting learners in MOOCs are discussed in the end.