This study aimed to assess the degree to which Indonesian secondary school EFL teachers have integrated 21st-century skills into their teaching and to investigate teachers' perceptions of their understanding of these skills and the significance of training for skill integration. Furthermore, the study sought to determine whether differences in perceptions regarding 21st-century skill integration existed between gender, school levels, and age. A survey of 141 teachers across 11 regencies or cities in a province in Indonesia was conducted. Results showed that the integration of 21st-century skills was unsatisfactory, as the frequency of integration was only between 1-3 times per month on average. Although half of the teachers had good knowledge of 21st-century skills, 40% had never received training on this topic. No significant differences were found in the level of integration based on gender and school level. However, age was a significant factor. Implications for policymakers, curriculum designers, pre- and in-service training programs, and teachers in the Indonesian context are put forward.