This paper aims to investigate the use of Facebook in enhancing English writing skill of Indonesian students in the secondary high school context. The result of this research is hopefully beneficial to overcome English writing difficulties of secondary high school students in Indonesia. The discussion informs that Facebook utilisation in teaching writing improves learners motivation to write in English, increases grammar mastery of the students, and provides abundant learning materials for the learners to develop their English writing ability. The result of this study will be useful as a reference for English teachers to adjust Facebook use into their teaching practice in order to help students in improving their English writing skill.