Personality traits of teachers are critical to their teaching reflections as well as students learning and satisfaction. However, there is no guiding framework about which personality factors and style of communication are important for teachers' communication effectiveness during their classroom teaching. The current research studies the impact of personality traits on Communication Effectiveness (CE) of teachers during their classroom teaching and the mediating role of their Communication Style (CS). A sample of 250 teachers from Indian higher education institutions participated in the exploratory study. The study applies PLS-SEM, a theoretical model was proposed and the results point to a total mediating impact of CS on the relationship between personality and CE. The direct effect of the personality traits on communication effectiveness, although positive becomes insignificant, indicating that to a major extent the influence of personality traits on communication effectiveness is explained by the communication style of the teachers. "Conscientiousness" and "Extraversion" personality traits are the most significant personality traits which bring about communication effectiveness in teachers through their "expressive" and "precise" communication styles. Validation of the proposed model will facilitate the teachers to assess their personality traits and identify the most suitable teaching styles which will make their classroom teaching effective thus, enhancing students' class participation and academic performance.