The purpose of this study was to examine the practices and challenges of school-based teachers' continuous professional development implementation in secondary schools of Hawassa City Administration. The study employed a descriptive survey design with both quantitative and qualitative method. The sampling technique used in the study was availability and simple random sampling technique. The sample size was 101 teachers (31 females and 70 male), four department heads, four principals, and four continuous professional development facilitators. The data gathering tools were through questionnaires, interview, and document analysis. Principals, senior teachers and Continuous Professional Development (CPD) facilitator were involved in the in-depth interview. The questionnaire was administered to 101 teachers, of which 101 of them were properly filled and returned. The data gathered through the questionnaire were analyzed using percentage, mean and standard deviation while the data gathered through interview and open-ended questions were narrated qualitatively. Results of the document analysis were also substantiating the quantitative analysis. The findings of the study revealed that the extent to which teacher's engagement in professional development activities such as mentoring, portfolio development, conducting action research, facilitating group discussions and peer observations, and evaluating the overall successes and failures of the implementation processes were inadequately implemented. The school principals, professional development facilitators, senior teachers as a mentor, the City Education Office Experts were providing insufficient support for the teachers. The major challenges identified were, lack of teachers motivation/interest, lack of adequate training, lack of skills in conducting action research, lack of adequate resource in conducting Continuous Professional Development, lack of trained facilitators, insufficient allocation of budget, lack of peer coaching and peer evaluation, and high workload to those who participate in continuous professional development were identified in this study as the serious challenges of Continuous Professional Development realization in secondary schools of Hawassa City Administration. Therefore, conclusions and recommendations were forwarded based on the finding of the study.