The aim of this study was to investigate the effect of exposing learners to authentic online reading materialson their written outputs (writing summaries and reflective essays). The quantitative method specifically the one-shot pretest-posttest experimental design was adopted. An online course was designed learners writing through reading authentic materials. Through the guidance of the teacher, learners discovered the conventions of paragraph writing from their critical reading of authentic materials and then applied these conventions in their own writings. A writing test with an analytic rubric was designed to measure students' writing performance. Results of the study about writing summaries and writing reflective essays show a significant improvement in students' performance after their critical reading of authentic materials. The study recommends the use of authentic online courses for enhancing EFL writing performance.