The study was aimed to compare the process of teachers’ performance evaluation used in public and private secondary schools in Karachi as perceived by their principals and teachers. The study was descriptive research both qualitative and quantitative in nature. The sample of the study include 50 principals, 25 from public schools and 25 from private schools and 250 teachers, 125 from public schools and 125 from private schools located in five districts in Karachi city. The study was carried out with the help of two structured questionnaires comprising of the same items that were closed- ended. Section I included demographic qualities of respondents, whereas section II was designed having 56 items in which statements about teacher’s performance evaluation process were grouped under six themes namely: the indicators of performance evaluation instrument, purpose of the process of teacher’s performance evaluation, quality of the process of teacher’s performance evaluation, training involved to participate in (for teachers) and to conduct (for principals) the process of teacher’s performance evaluation, feedback given by the principals to teachers to enhance teachers’ performance, students’ performance and also their own performance, and relationship between principals and teachers in the process of teachers’ performance evaluation. The data was collected through interview method and responses were rated for each of the statements using a five-point Likert scale. The instruments were validated through content validity and face validity. Statistical Package for Social Sciences (SPSS) Version 21 was used for data analysis. Descriptive statistics, Independent-Samples T Tests and Chi-square tests with significance noted at p < 0.05 were used for hypotheses testing. The researcher confirmed the study is free of bias and the questions were clearly understood to be completely and properly answered. The results of this study concluded that both public and private schools have all indicators on the teachers’ performance evaluation instrument related to important aspects of teaching and learning that are used as criteria to evaluate performance of teachers. Majority of principals and teachers perceived that the most important indicator was “teacher’s knowledge of subject possessed by teacher” used on teachers’ performance evaluation instrument in both public and private schools of Karachi. Majority of teachers both from public and private schools perceived the performance evaluation process as threatening for the teachers, in contrast majority of the of the principals both from public and private schools did not consider performance evaluation process as threatening for the teachers. While inquiring about the purpose of performance evaluation, majority of the principals and teachers from public and private schools demonstrated highest percentage for purpose “to raise the standards of teaching and learning’ followed by the response “to improve teachers’ performance”. Professional development of teachers and the accountability of teachers were ranked as third in importance. The results of the study highlighted the quality of teachers’ performance evaluation process and concluded that a proper system of teachers’ performance evaluation exists in both private and public secondary schools but the quality of teachers’ performance evaluation systems is better in private schools as compared to public school in Karachi as the performance of teachers is not monitored constantly in public schools on the other hand the performance of teachers in private schools is monitored on regular basis, the results of performance evaluation accurately reflect a teacher’s ability in private schools, in contrast, the results of performance evaluation do not accurately reflect a teacher’s ability in public schools, the number of classroom observations of teacher by the principal to evaluate instructional skills of teacher were adequate in private schools, in contrast the visits by principal were not adequate in public schools, the rating system used to evaluate teachers is useful for the growth of principals and teachers in private schools but in public schools the rating system used to evaluate teachers is not useful for the growth of teachers and principals. Both public and private schools unanimously agreed that the feedback received from teachers’ performance evaluation is used to improve teachers’ performance, to highlight teachers’ strengths and make them aware of their weakness and for professional development of teachers. There was a lack of training for the principals and teachers both from public and private schools to evaluate or to participate in teacher’s performance evaluation process. There was a conflict of opinion between principals and teachers about briefing of indicators of teacher’s performance evaluation instrument to the teachers of school by their principals. Whereas the principals both from public and private schools stated that in pre-observation meeting they brief teachers about the indicators of teacher’s performance evaluation instrument, in contrast, most of the teachers both from public and private schools stated that in pre-observation meeting, the principal did not brief teachers about the indicators of teacher’s performance evaluation instrument. There was a good relationship between principals and teachers in private as well as public secondary schools. Most of the principals and teachers from public schools denied about the authority of principal to remove the teacher from service on poor performance, oppositely most of the principals and teachers from private schools accepted the authority of principal to remove the teacher from service on poor performance. The results of this study concluded that overall there was no significance difference in teachers’ performance evaluation process in public and private secondary schools in Karachi, however, the teachers’ performance evaluation in private schools is better as compared to public schools in terms of quality. Unlike private schools, the performance of teachers in public schools is not monitored regularly, the results of performance evaluation do not accurately reflect a teacher’s ability, and the rating system used to evaluate teachers is not useful for the growth of teachers and principals as perceived by the respondents. In Pakistan there is a paradigm shift from Annual Confidential Report (ACR) where the results of performance evaluation were not shared with the teachers rather were kept “confidential” has to the philosophy of Performance Evaluation Report (PER) system in public schools and the same have been implemented, the process still has not involved both appraiser and appraisee to greater extinct. The private schools have some flaws in performance evaluation system of teachers but the situation in public schools is very critical. The study is expected to create awareness among principals and teachers about the importance of a sound performance evaluation system for teachers to improve their performance and achieve better results of their students by enhancing teaching/learning process in class room thereby improving the quality of education. Information provided might also be used to improve teacher evaluation procedures currently used in public and private schools of Karachi.