This research study aims to unravel the influence of in-service training programs on the teaching-learning process of secondary school teachers in Khyber Pakhtunkhwa, Pakistan. The study argues that teachers play a critical role in shaping the future of their students, and the quality of a nation's academic performance is linked to the quality of its teachers. Thus, it is essential to improve the quality of teacher education. Qualitative narrative research was employed in this study. The researcher selected five public girls' secondary schools through convenient sampling in district Mardan. The researcher selected ten secondary school teachers, and participants were selected using a random purposive technique. Semi-structured interviews were conducted following the saturation level of the interview questions. This research study furnished valuable findings with reference to in-service training that will assist in transforming teachers with sophisticated and constructivist teaching-learning processes. This research study accomplished recommendations at the teacher-educator level, policy level, teacher level, and student level. It's recommended that teachers should focus on reflective thinking and teacher group discussions in an attempt to make a more effective classroom. Teacher educators should empower teachers by reshaping their naive and traditional teaching practices. Realistic efforts need teachers' professional development with follow-up supervision by competent and dedicated trainers.