Teachers who teach English as a foreign language (EFL) should constantly develop their skills and knowledge by taking part in professional development programs (PDPs) which keep them aware of the most recent teaching trends. This mixed method study seeks to explore how PDPs influence EFL teachers' teaching practices in activating 21st century skills, and therefore their students' acquisition of these skills. It also examines the correlation between EFL teachers' activation of 21st century skills and their students' acquisition of these skills. The study used a sequential explanatory research design by utilizing questionnaires and semi-structured interviews. The results revealed that the two dimensions of 21st century skills that got the highest level of activation were the collaboration and communication skills. Furthermore, the results showed that the students acquire all 21st century skills with different levels of acquisition. Finally, the results showed that EFL teachers' activation of 21st century skills had no significant direct correlation with students' acquisition of these skills. These findings could provide insights on the area of PDPs that need to be researched more in different contexts. They also suggested that PDPs designers should incorporate all dimensions of 21st equally to be activated accurately by teachers in higher education institutions.