Despite the popularity and the importance of MOOCs in global education in recent years, they have not become the focus of self-efficacy studies. In addition, most available MOOC research resides in Western economies, not in Asian countries. No studies up to this point have explored the change in engineering student self-efficacy before and after they finish a MOOC or the relationship between engineering students' self-efficacy and academic performance in a MOOC learning environment. This present study examined if there were any changes in the self-efficacy levels of a group of students before and after they attended a blended MOOC on English Technical Writing skills. It explored the relationship between self-efficacy and academic performance and looked for possible differences in self-efficacy and academic performance with respect to different demographic variables. A Paired-samples t-test helped to measure differences in self-efficacy scores at the beginning and end of the course. Pearson correlation was conducted to examine if self-efficacy predicted students' course grades at the end of the course. Descriptive analysis, t-test, and ANOVA were used to measure the differences between the mean scores of self-efficacy and academic performance regarding different demographic variables. Results showed that students became more self-efficacious after they attended the blended MOOC. Self-efficacy significantly predicted academic performance. Students who reported higher self-efficacy levels gained better scores. Participants differed significantly in their self-efficacy and academic performance in relation to age group, English proficiency level, and educational level. Suggestions for future research are made based on the results of the study.