Managing relationships between/with students is one of the main duties that teachers are asked to fulfill, which becomes even more challenging in multi-ethnic/multicultural educational contexts. Responding to the need for culturally-qualified training for school professionals and given the increasing use of Massive Open Online Courses (MOOCs)—often without evidence supporting their efficacy—this study will evaluate the potential of a tailored MOOC—designed to tackle overt/covert discrimination and foster inclusion and culturally responsive teacher–student interactions—to promote teachers’ awareness and competence in conflict management. Overall, 206 Italian teachers experienced the MOOC, of whom 99 completed the Rahim Conflict Management Inventory-II, assessing Conflict Management Styles (Integrating, Obliging, Compromising, Dominating, and Avoiding) pre- and post-MOOC. Potential changes in the adoption of Conflict Management Styles after completing the MOOC were evaluated. After completing the MOOC, there was a reduction in teachers’ recourse to the Avoiding and Obliging styles and, of note, more informed/targeted use of the Dominating style. These findings provided evidence-based contributions sustaining that the MOOC may effectively foster a more aware, engaged, and active pattern for managing relationships and conflicts within classes, thus potentially having a tangible positive impact on the real everyday life of teachers experiencing this training and their students.