Bondo is among the Sub Counties in Kenya with low academic performance in Chemistry subject. This could be as a result of several factors which in turn could be contributing to wastage grades in national examinations in secondary schools in Kenya. The purpose of this study was to establish the effect of academic performance of Chemistry subject on wastage grades in secondary schools in Bondo Sub County. The main objective of this study was based on the purpose of the study. The study was informed by Jean Piaget’s constructivism theory of knowledge and its examination linked to the concept of the study. The study adopted a correlation research design. The population comprised of the 338 teachers and 1 Quality assurance officer in the Sub County. Stratified random sampling was used to identify and place sub groups within the population, purposive random sampling was then applied in each sub group to form the actual sample per school. Instruments of data collection were questionnaires, interviews and document analysis. Reliability of instruments was checked by piloting using test and retest method in 10% of the population that did not participate in the study. Face, content and construct validity was ascertained by experts from the department of Department of Curriculum and Educational Management. Quantitative data was analyzed with aid of Statistical Package for Social Sciences (SPSS), version 25.0. It generated both inferential and descriptive statistics such as correlation coefficients, frequency counts, chi square tests, averages and percentages while qualitative data was analyzed continuously using content and thematic issues and presented by narrations and direct quotes, in line with the study objectives. The findings revealed that the Pearson correlation co-efficient, r = 0.078, a positive correlation between attitude and academic performance in the subject in over 80% of the schools. In cases where responses among the categories varied, A Leven’s test was applied to test if the variance in attitude of student towards Chemistry as given by teachers and heads of departments is equal. The p-value is 0.487 and the test was carried out at 95% level of confidence or at an alpha, α = 0.05. The test statistics was 0.112 with 76 degrees of freedom and the p-value of the wider hypothesis is 0.911. At alpha level of 0.05, that is if we wanted to be 95% certain before we reject the null hypothesis, then we could not do this with the p-value of 0.911. Findings revealed that teaching methodologies and resources played a role in shaping academic performance of Chemistry subject. The study recommended that education stakeholders including the school principals should endeavor to provide comprehensive development programs for teachers of Chemistry such as workshops for training on current issues and trends emerging in methodology and instruction so that they are up to date with relevant skills and so as to seal the loopholes and insufficiencies that derail performance of the subject both in internal and national exams. The findings of the study might be useful to education policy makers, education planners and education stakeholders as a whole in improving academic achievement so as to minimize wastage grades in national examinations in Bondo Sub County and in Kenya as a whole.