This study explored the impact of Six Thinking Hats blended learning program-based Moodle on ESP university students' writing skills and academic flow. Four instruments -designed by the researcher- that included: (a writing skills checklist, a writing skills test, a writing scoring rubric, and an academic flow scale) were used for collecting data. The research adopted the quasi-experimental design using two groups: an experimental group (n = 33), and a control one (n = 33). The researcher taught both groups: the experimental group was taught using Six Thinking Hats blended learning program-based Moodle. In contrast, the control group was taught through the regular teaching method. Research results revealed statistically significant differences between the mean scores of the experimental and the control group students in the writing skills tests and the academic flow scale in favor of the experimental group. Besides, the effect size of the six thinking hats blended learning program-based Moodle was high.