Dynamic assessment (DA), based on Vygotsky's Sociocultural Theory, integrates instruction and assessment into a single activity through interactive dialog between the mediator and learner to promote development. This research utilized the interactionist DA to assess and enhance five types of listening inferential abilities of Chinese EFL learners. Micro-genetic analysis was used to track the developmental trajectory. The study compared four students' independent and mediated performances across the pre-test, post-test, and transfer test. Results showed that DA positively influenced the students' listening inferential abilities, with all five inference types showing varying levels of improvement after DA. The findings can be grouped into three primary categories: (1) Students demonstrated the most significant enhancement in thematic inference during both the post-test and transfer test; (2) Students faced challenges with predictive and motivational inference; (3) Although progress in the transfer test remained below average, there was notable advancement in conversational implicature in the post-test. Conversely, the situation with attitudinal inference showed the opposite trend. This study demonstrated that implementing DA could offer a nuanced understanding of EFL learners' listening inferential abilities and provide valuable empirical support for the use of DA in future foreign language classroom instruction.