The present study examined unique and shared contributions of Korean (first language) phonological, orthographic and morphological awareness (PA, OA and MA, respectively) to English (second/foreign language) spelling among 287 fourth‐grade, fifth‐grade and sixth‐grade Korean children. Korean measures of PA, OA and MA were administered, in addition to English vocabulary and spelling measures. Results from structural equation modelling showed that PA, OA and MA were caused by one common construct, metalinguistic awareness (META), and the contribution of Korean META to English spelling was statistically significant, controlling for English vocabulary. In particular, Korean MA and PA played unique roles in explaining English spelling; whereas Korean OA did not significantly contribute to English spelling. Findings from the present study provided empirical evidence of first language META transfer effect on second/foreign language spelling development. Educational implications and future research ideas are discussed. Copyright © 2017 John Wiley & Sons, Ltd.