This study used a mixed-methods research design to examine how preschool teachers in Taiwan implement the embedded executive function (EF)-supporting activities within the classroom and the consequent effects on children’s EF and oral language. Twelve teachers and 82 children from two preschools participated in the study. All teachers received training and developed a set of strategies employing embedded EF-supporting activities within the classroom. The study measured children’s EF and oral language after a 12-week period. Although significant effects on children’s EF were not observed for the overall sample, significant improvement in children’s oral language was indicated by the markedly higher scores compared with the pretest. Further analysis indicated that the effects were driven by the preschool with lower EF and oral language. The results demonstrated that EF-supporting activities can enhance the quality of the classroom, including increasing the speed of clean-up, encouraging children to focus on a goal and be responsive to the teachers’ directions, and more time for group discussion. The results recommend that teachers need more coaching support. Researchers need to facilitate teachers playing a more active role in designing EF- supporting activities and incorporate more time points to examine the long-term effects on children’s EF skills and academic learning.