As generative artificial intelligence (GenAI) technologies develop, secondary teachers face the challenge of helping students use GenAI effectively and responsibly for learning. Based on the large-scale EDUCATE project's video recordings of naturally occurring teaching (i.e., without teacher–researcher collaboration), this study examined authentic GenAI practices in highly digitalized language classrooms. Shortly after GenAI became mainstream, we screened 75 English and Norwegian lessons across 20 classrooms in five secondary schools during 2023–24 to identify lessons with GenAI. We identified GenAI practices in 14 lessons across 10 classrooms in 4 schools, and we analyzed these lessons using reflexive thematic analysis. The findings showed that the GenAI-integrated teaching required teachers' use of professional digital competence and targeted both students' subject-specific competences and their AI literacy. The study highlights important implications for secondary teaching when combining GenAI with subject-specific teaching, emphasizing the need to support students' responsible GenAI use.