This study analyzes the association between teachers’ self-efficacy beliefs in educational Internet use and the perception levels of their technological pedagogical content knowledge (TPACK). The findings show statistically significant relationships among the knowledge domains in technology, pedagogy, content, and their intersections. The findings show all knowledge types contained in the TPACK model are significantly and strongly related to the self-efficacy beliefs in educational Internet use. The findings indicate that teachers who understand TPACK will have higher self-efficacy toward Internet use and therefore better integration habits around using the Internet. The results clearly show that better TPACK knowledge is correlated with higher self-efficacy in educational Internet use.