Education for sustainable development recognizes the ways, in which teachers improve education, by utilizing their skills to the fullest extent and reconsidering the conditions of the teaching profession. The relationship between teachers' professional identity and teachers' emotions is an issue that needs to be studied as a basis for improving the effectiveness of their professional activities. Thus, a standardized questionnaire was used to describe the characteristics of Vietnamese secondary teachers and the influence of teacher professional identity (TPI) on working emotions. The study was conducted in Vietnam using two survey instruments aimed to determine the role of TPI contribution in the different dimensions of teachers' emotions (anger, fear, joy, love and sadness). Findings revealed that a higher level of TPI social dimension was among participating Vietnamese teachers, and a lower level was towards career with negative emotions such as anger, fear and sadness. In addition, higher levels of the institutional dimension of TPI were associated with lower levels of teachers' feeling of joy in their career; and when the level of the personal dimension of TPI was higher, teachers' sense of love towards their profession was higher. Three implications of the study are proposed to help promote teacher identity, in ways that contribute to positive emotion in executing their teaching task. In other words, when teachers had a higher motivation, satisfaction, and commitment, they could perceive teaching as a noble job and be full of positivity. This made teachers ready for professional development in compliance with sustainability education goals.