Framed within the discussions of the knowledge base for language immersion teachers, this article presents a qualitative case study of a first-year Grade 2 French immersion teacher's enactment of his systemic functional linguistic (SFL) knowledge to position his students in a culturally sustaining genre pedagogy. We examined interactive events and interview data to understand how Ahmed deployed his SFL knowledge base to position four African American students in classroom interactions as they deconstructed and reconstructed focal genres in this second-grade French immersion classroom. Our findings revealed that Ahmed positioned his students in three ways: as an inclusive classroom community, as readers and writers, and as language analysts. Likewise, the students took up roles as genre analysts, active language users, and engaged community members. The findings also demonstrated that Ahmed selectively deployed his linguistic resources in varieties of French and English to connect with his students, create community with them, and achieve his instructional goals within a translanguaging space (e.g., Tian, 2021; Wei, 2011). These findings point to the potential of SFL and translanguaging pedagogy as a flexible and dynamic knowledge base for enacting culturally sustaining immersion education.