Studies have found that morphology awareness could assist writers to increase productive vocabulary (e.g. Green et al., 2003; McCutchen & Stull, 2015), reduce vocabulary errors (e.g. Karakas, 2012; Ririn, 2010), and produce complex sentence structures using various forms of words. Postgraduate students as second language users of English (L2) were found to experience lack of vocabulary and have difficulties in their academic writing. Researchers have been concentrating on examining the relationship of morphological awareness with vocabulary reading, reading comprehension, receptive vocabulary knowledge, and spelling; however, there is still a shortage of studies examining the relationship of morphological awareness with academic writing, particularly among L2 postgraduate students. Therefore, this study aims to examine the correlation of morphological awareness with academic writing and investigate the extent to which the dimensions of morphological awareness and productive vocabulary knowledge predict the success of postgraduate students' academic writing in an ESL context. The results showed that there was a significant correlation between morphological awareness and academic writing. The synthetic dimension of morphological awareness had a stronger contribution than the analytic dimension to the L2 postgraduate students' academic writing. The results also showed that learning and teaching morphology could bring benefits to L2 postgraduate students, allowing students to improve their productive writing skills and enabling them to produce texts and convey their ideas meaningfully.