The integrative approach of teaching Science, Technology, Engineering and Mathematics (STEM) has been advocated as a pedagogical means to advance education for the 21st century. However, there is a lack of validated instruments that are theoretically grounded to account for the various forms of knowledge that teachers need in order to effectively implement STEM education. This study adopts the technological pedagogical content knowledge (TPACK) framework to develop the Technological Pedagogical STEM Knowledge Survey to assess teachers' self-efficacies of the proposed dimensions of knowledge. It also investigates the interrelationships of the four knowledge dimensions (i.e., technological pedagogical science knowledge [TPSK], technological pedagogical mathematics knowledge [TPMK], technological pedagogical engineering knowledge [TPEK] and integrative STEM) proposed in this paper. A total of 314 science, mathematics and technology teachers from China responded to the online survey. Both exploratory and confirmatory factor analyses indicated adequate validity and reliability of the survey for measuring teachers' self-efficacies for STEM from the TPACK perspective. The structural equational model indicates that the teachers' efficacies of integrating technology into science, mathematics and engineering subject predict their efficacy of integrative STEM teaching. Moreover, teachers' TPEK is the strongest predictor of their efficacy for teaching integrative STEM. Overall, the findings support that the TPACK framework could be theoretically useful for promoting teachers' efficacies for STEM education. Practical implications were discussed in this study.