This longitudinal inquiry explored metalinguistic awareness in bilingual word reading evolution amid Malay–English bilingual children in Singapore. Participants were evaluated with the same tasks twice with a 1-year interval from Grade 3 to Grade 4 in phonological and morphological awareness and derived word decoding in both English and Malay. Structural equation modeling assays disclosed that both types of metalinguistic awareness significantly predicted derived word reading in both languages. Ensuing cross-lagged panel modeling found construct-level transfer facilitation effect from Malay on English for phonological awareness but conversely from English on Malay for morphological awareness. Neither type of metalinguistic awareness exerted a transfer facilitation effect on word reading. These findings elucidate the developmental mechanism of cross-linguistic transfer in biliteracy acquisition.