The international Bebras challenge (BC) aims to raise the students’ interest in computer science (CS) and contribute to their problem-solving and computational thinking (CT) skills development. Through solving short conceptual tasks that are close to real-life context, students obtain the essential literacy needed to be successful in the modern world. Although the initiative has been running for about 20 years, teachers’ motivation to engage with students in this challenge remains underexplored. This study employs self-determination theory as a theoretical framework and the work tasks motivation scale for teachers as an instrument. Data collected from 334 teachers across Estonia, Hungary, and Lithuania were analyzed. The results showed teachers’ motivation most significantly stemmed from intrinsic motivation and identified regulation. There were no significant differences in all types of motivation between male and female teachers or teachers with different years of teaching experience. However, teachers who were more experienced in engaging in the BC demonstrated higher levels of almost all types of motivation. Mature teachers were more externally motivated than their younger colleagues. Teachers who used the Bebras tasks in their lessons had a higher level of intrinsic motivation and identified regulation than those who did not use these tasks. Teachers teaching various subjects showed different levels of identified regulation. The study provides implications for teachers, school administration, and the BC organization.