Technological revolutions have huge impacts on various disciplines of life, including language education. Therefore, the employment of new technologies like artificial intelligence (AI) has been the focus of both research and practice. However, as basic practitioners, most language teachers’ acceptance and use of EdTech seems fundamental and basic. Hypothesizing that training would change the teachers’ confidence and acceptance levels in using AI chatbots, this study examined such a relationship would change among a group of 27 Vietnamese teachers of English before and after being trained and coached on developing these tools. We adopted a mix-methods research design and adapted the UTAUT2 framework. We used a set of surveys to collect quantitative data to investigate the extent of the change. Focused group interviews with the participants were organized during a 3-week training period to gain insights into the change. Employing T-test, Cohen’s d effect size and content analysis, the study found that the trained teachers’ confidence varied. Also, their acceptance of the chatbot significantly increased after the traning. The findings suggest that adequate training could greatly benefit foreign language teachers to accept EdTech.