This study aims to examine the effect of Mental Health and Trauma Counselling (MHTC) module toward counsellors’ competency in handling mental health and trauma counselling among school counselling teachers. In addition this study also examines the effect of MHTC module towards sub constructs’ competencies namely knowledge skills and awareness based on three demographic aspects that are related to subjects such as sex age and level of experience of attending MHTC workshop. Quasi-experimental pre-test and post-test treatment group design was used in this study. The sample consists of 48 high school counselling teachers (14 males and 34 females) selected using purposive sampling within Selangor and Perak. Mental Health and Trauma Counselling Skills Instruments (MHTCSI) which contains three sub constructs competencies namely knowledge skills and awareness are used in this study. Quantitative data of experimental study are analyzed using SPSS version 20. Descriptive statistics of mean percentage and standard deviation and inferential statistical of t-test were used to analyze the data. The results show that MHTC module is found to be descriptively effective for enhancing the counsellor’s competency and sub constructs’ competencies namely knowledge skills and awareness based upon gender age and level of experience of handling mental health and trauma counselling. The findings by inference using paired sample t-tests have proven that there are significant differences in pre-test and post-test for construct competency [t (47) = -13 865 p <.05] and sub construct’ competencies of knowledge [t (47) = -12 197 p <.05] skills [t (47) = -10 592 p <.05] and awareness [t (47) = -10 392 p <.05]. Based on the results this study shows that mental health and trauma counselling workshop has successfully enhanced the counsellors’ competency and all sub variables’ competencies such as knowledge skills and awareness. The implications of this study would directly enhance the efficiency of counselling practices and counsellor education in the context of mental health especially in the field of trauma counselling among school counselling teachers.