Morphological awareness is essential for language and literacy development, yet its underlying structure remains unclear, especially in Chinese-English bilinguals at different ages. This study tested 467 hong Kong bilingual children in Grades 2, 5, and 8 on their morphological awareness in both Chinese and English. Confirmatory factor analysis was conducted to examine whether morphological awareness in each language is a unidimensional structure, a multi-dimensional structure by task modality (i.e. receptive vs. expressive), or a multi-dimensional structure by stimulus level (i.e. Chinese: word, character, radical; English: free vs. bound morpheme). The results indicated that for L1 Chinese, morphological awareness was unidimensional in Grade 2, multi-dimensional by task modality in Grade 5, and unidimensional in Grade 8. L2 English maintained a unidimensional structure across all grades. These findings underscore how the dimensionality of morphological awareness is shaped by language-specific features and developmental changes.