This qualitative study explored teachers’ knowledge and teacher efficacy about implementing technology-integrated flipped classroom (FC) in higher education. Using the technological pedagogical content knowledge (TPACK) framework and teacher efficacy theories, the study probed the experiences and perceptions reported by 12 university teachers of English as a foreign language. Six themes emerged from the study. Themes 1 to 3 depicted how the EFL teachers practiced the three essential teaching tasks of technology-integrated FC. By incorporating the instructional design of FC into TPACK constructs, the study developed a new FC-situated TPACK framework. Themes 4 to 6 revealed that the teachers’ sense of efficacy increased overall but fluctuate slightly. Factors improving teacher efficacy included positive changes in student performance, supportive leadership and climate, effective group work among colleagues, and open-mindedness toward technology. While factors decreasing teacher efficacy encompassed adherence to a unified teaching model imposed by the department, technology’s non-user-friendly, and impersonal characteristics. This study provides a comprehensive view of how the sampled teachers applied FC-situated TPACK. Its findings also enhance the understanding of teacher efficacy, particularly in relation to FC instruction.