This study investigates the role of morphological awareness in the incidental learning of Mandarin Chinese characters among Chinese as second language (CSL) learners. Participants of the study were 20 college-level international students, uniformly Thai in language background, enrolled to study CSL at Southwest University, Chongqing, China. The research questions were investigated through two experiments, one administered to measure their L2 morphological proficiency in Chinese and the other to pinpoint the overall contribution of morphological awareness in incidental Chinese character learning through extensive reading as well as how such a contribution may vary when different dimensions of word knowledge are concerned. The results indicate that while higher L2 language proficiency can in general correspond to higher L2 morphological awareness, which in turn benefits the incidental learning of new words, morphological awareness plays a stronger and more explicit role in facilitating the incidental Chinese character learning for intermediate learners relative to advanced learners. In addition, intermediate learners, compared to advanced learners, tend to rely more heavily on character-internal and orthographical information when learning novel characters.