Abstract: This study aimed to find out the readiness of teachers who taught principles of accounting subject at secondary schools in terms of knowledge, skills and attitudes towards the mastery learning teaching approach. A set of questionnaires was used in this study to measure their readiness. The samples were 80 teachers who taught principles of accounting subject from secondary schools in Negri Sembilan state of the Peninsular Malaysia. They were randomly selected from all the secondary schools in the state. The descriptive and inferential statistical tests were used such as frequency, mean score, percentage, t-test and analysis of variance at the significant level of p<0.05. The mean scores showed that the readiness of the teachers from the aspect of knowledge was low, the level of skills was high and the attitude was positive. The t-test result showed that there was no significant difference in the attitude towards using mastery learning teaching approach based on gender. The one-way ANOVA test showed that there was no significant difference in the teachers’ attitude towards mastery learning based on age and options and significantly different based on number of years in teaching. The post-hoc LSD test showed that teachers who had taught >15 years have positive attitude towards the mastery learning approach. The implications of this study is teachers need to be provided with proper knowledge of mastery learning teaching approach because their readiness level in terms of teaching skills and attitudes were good.