Teacher professional development is a continuing process that, when effectively implemented, improves teaching skills and subject knowledge, leading to enhanced instructional quality and better student learning outcomes. This study assessed the current practice of continuous professional development (CPD) for teachers' instructional quality in Woliso Town secondary schools. A mixed-methods research approach was employed. The sample included 175 secondary school teachers (147 males and 28 females) selected purposively for quantitative data collection. Additionally, the school principal and academic vice-principals were selected for qualitative data. Quantitative data were collected from 145 secondary school teachers who teach subjects assessed by educational examination services for university entrance. Six one-on-one interviews were conducted with secondary school principals and academic vice-principals. Quantitative data were analyzed using SPSS version 25 and presented using descriptive statistics such as mean, standard deviation, and percentage. Qualitative data were analyzed thematically and presented narratively to substantiate the quantitative findings. The results revealed that the traditional model of teacher professional development is both superficial and fragmentarily practiced, which does not meaningfully contribute to teachers' instructional quality. Moreover, teachers are often not voluntarily engaged in CPD activities due to various factors, including life pressures, lack of motivation, insufficient recognition, and the absence of systematic evaluation of teachers' progress in instructional quality. Based on these findings, it is recommended that the government, education policy developers, and academicians reform the existing CPD framework using alternative teachers' professional development. Furthermore, education stakeholders at all levels should develop and implement reformed CPD manuals to ensure consistency across schools through national or regional guidelines.