This research aimed to enhance the 21st-century skills of students at Sarakulnawitaya School by focusing on communication skills, creativity, critical thinking, and collaboration. The research methodology was Participatory Action Research. The objectives of the research were threefold: (1) change occurred, (2) learning developed, and (3) knowledge gained from practical experience. The research involved 20 teachers as co-researchers and 50 students. The results of this study compared the average performance across three phases: before and after the implementation of "Cycle 1," and after the implementation of "Cycle 2." The findings indicated that: (1) The implementation of 55 predetermined strategies for enhancing learners' skills in the 21st century resulted in the increase of the average scores from 2.42 to 2.74 and 3.02, respectively, while students' communication, creativity, and analytical thinking, and teamwork skills improved as reflected in their average scores of 2.46, 2.77, and 3.06. (2) The research team, participants, and educational institution gained knowledge and learning from the various implementation phases, particularly in terms of team awareness, mutual assistance, systematic problem-solving, and collaboration. (3) The research yielded valuable insights into the relationship between driving forces that hinder change, methods for overcoming resistance, and the resulting changes. This knowledge is referred to as the "Teacher-Involved Model for Enhancing 21st-Century Learner Skills in Sarakulnawitaya School."